Now that Donald Trump really is the Republican nominee, the neverTrumpers have a choice. They can either join the Trump train, they can vote for HRC, or they can stay home. Or, they can vote third party, but that's the same thing. So, does it really make sense to, as George Will asked them to do, grit their teeth through a Clinton administration and hope to beat her in 2020?
Maybe, so here's my attempt to separate the rational from the irrational neverTrumpers.
Domestic vs. foreign policy
Let's first distinguish between those conservatives interested in foreign policy and those interested in domestic policy. On domestic policy, Trump will sign the Paul Ryan budget and appoint judges from the Federalist Society. Will he do it out of sincere principle? No, because Donald Trump has no principles. Yesterday, I addressed the neverTrumpers who oppose him out of distrust, and might heckle him. If they care about domestic policy, that's nuts. HRC would veto the Paul Ryan budget, so why should the true conservative neverTrumpers care that Trump wouldn't sign it with a song in his heart? HRC would nominate judges far to the left of Merrick Garland, so why should true believer neverTrumpers care that Trump wouldn't be... fantasizing... about Scalia while making his appointments? The basic point is that Trump is not a true believer. But, he would certainly govern in a more conservative manner than Clinton, so any neverTrumper who votes against Trump, or abstains because Trump isn't a true believer is irrational. (Of course, voting is irrational anyway because your vote won't make a difference, but that's just me being unmutual again...)
Notice, then, where Paul Ryan and Mitch McConnell stand. I've written before that both of them need Trump to win. Paul Ryan can't survive divided government. In fact, I kinda-sorta predicted Boehner's downfall in a paper presented at the 2014 American Political Science Association (available here). The gist was that the combination of extreme polarization and divided government forced Boehner into a position in which he needed to split his own caucus, forcing a bunch of Republicans to break off and join Democrats to raise the debt ceiling with no concessions unless they wanted to be blamed for crashing the economy. That couldn't be stable, and it wasn't. Ryan resisted the speakership until Boehner raised the debt ceiling for the rest of the term, hoping for a Republican victory in November because he knew he'd be in the same position, and he knows he can't survive that. Ryan needs a Republican president, or he gets Boehner-ed.
McConnell's position is slightly less precarious. Slightly. When Scalia croaked, McConnell immediately announced that the Senate wouldn't even hold hearings on any Obama nominee. Astounding and unprecedented. And if HRC wins, what can he do? Can he really back away from that and try a lame duck confirmation? If not, can he maintain a four year blockade? This gets really ugly.
So really, the domestic policy Republicans? Trump is as insincere as it gets, but so what? The alternative is HRC. I hear Mick Jagger singing in my head. I often hear voices in my head. Maybe I should get that checked out... Point: domestic policy conservatives are irrational not to get on board with Trump.
Foreign policy is another matter. First, the president has a lot more unilateral authority on foreign policy. War powers, intelligence agencies etc. And this is where we have to remember Sen. Mark Kirk (R-IL). A lot of his opposition to Trump is certainly posturing. He is a vulnerable incumbent in a blue state facing the most divisive Republican nominee at least since Goldwater. But he's not necessarily wrong. His critique of Trump is that the man is too reckless and impulsive to be trusted with the national security apparatus. People like to make jokes about Trump launching a nuclear war to retaliate against somebody for making jokes about the size of his hands. That is highly unlikely to happen. I wish I could say that the probability is zero, but let's be honest-- it isn't. In the realm of more realistic issues, put Trump's personality in the Cuban missile crisis, or similar situations, and human civilization might not exist. Of course, Trump would say that the crisis wouldn't happen because he is so tough that nobody would test his resolve like that, but that's bullshit. Let's look back at Reagan. For all the supposed toughness of the Reagan administration, the Soviet Union didn't crumble in fear. They built up their military, stepped up operations in Latin America, Afghanistan, and elsewhere, intelligence operations continued apace, and eventually, after Reagan, it crumbled mostly because centrally-planned economies are stupid and Karl Marx was a bloody moron who should be studied only so that we don't repeat the worst mistakes in history. Santayana, and all that. I love how Reagan worshippers attribute the fall of communism to their hero rather than the intrinsic superiority of capitalism. Have they no confidence in their own ideology? Sorry, social science rant.
Anyway, the basic point is that foreign policy decisions need to be made by people who are both intelligent and careful. This is actually where that stupid plagiarism thing matters. The way to compensate for Trump's ignorance of foreign policy and recklessness is if he surrounds himself with intelligent and sophisticated people. If he did that, the Melania Trump thing wouldn't have happened. Trump surrounds himself, not with the best and the brightest, but with sycophants, because he cares primarily about being feted. That's what truly scares the Mark Kirk types. The sincere ones, anyway.
Paul Ryan, Mitch McConnell, and the domestic policy types? They want and need Trump. They don't care that he is insincere. They want and need somebody who will follow the Grover Norquist model of the presidency.
Foreign policy types? They see through the Benghazi bullshit. They know that Trump is reckless, and worry that he might do something epically stupid, whereas HRC, while way too left for them, could at least handle a Cuban missile crisis-type-deal without destroying humanity. Trump couldn't.
So there you have it. A big part of the rational vs. irrational neverTrumpers is about foreign versus domestic policy.
Long versus short term
This is where things get harder, so I have less to say. Are you willing to lose in the short term for the long term gain? After the 2012 election, the Republican Party did a post-mortem analysis, and the conclusion was that the party needed to address immigration reform and be more inclusive. Trump moves the party in the opposite direction, both on policy and rhetorically. His language on immigration and towards Latinos will make it virtually impossible for Republicans to make any gains among Latinos for a generation if not longer. When Barry Goldwater ran for president as an opponent of the 1964 Civil Rights Act against Lyndon Johnson as the supporter, African-Americans went from leaning strongly Democratic to almost uniformly Democratic, and they never went back. Latinos may be on the verge of that, and if the Republican Party becomes the party of Donald Trump while the Latino population grows, that's a big problem.
This is where the destroy-the-party-to-save-the-party strategy comes in. Suppose you are a true conservative who hates HRC. How much harm will HRC do in four years? Then, how much harm will the Democrats do in every year after that if the party locks in the Latino vote the way they have with African-Americans? If the only way to stop that is to take down Donald Trump, is it worth it?
This is the calculation of the neverTrumpers who go further than Paul Ryan. When Donald Trump opposed the judge in his class action fraud case, first by calling him "Mexican" (he is US-born), then by claiming he has a "conflict of interest" because of his "Mexican heritage," Paul Ryan called it "textbook racism." But Paul Ryan still goes along with Trump. Why? He has to. See above. His short-term incentives are too strong. Those who don't have Ryan's short-term incentives might see things differently.
Republicans in California are still in the wilderness. Pete Wilson won a tough reelection fight in 1994 by championing a ballot initiative denying services to illegal immigrants. The consequence, though, was to mobilize Latinos in the state, and turn them strongly Democratic. The Republicans have only won statewide races there since under weird circumstances, like Arnie's victory in the recall campaign against Gray Davis.
The danger for Republicans is if Trump comes to define the party nationwide.
So, there's my attempt to distinguish rational from irrational neverTrumpers. Foreign vs. domestic policy, and long vs, short term. It can be rational for neverTrumpers to stay that way if they care more about foreign policy than domestic policy, or if they care more about long-term goals than short-term goals.