This is an incredibly short-sighted and shallow view.
Give this some real though for a moment. Just imagine that you - a pretty staunch progressive so far as I can tell - end up with a Dem candidate in 4 years that has a criminal record, is a demonstrated liar, and is absolutely vile in your opinion. Don't tell me it's impossible or would never ever happen with a Dem, use your imagination on this.
I'm in a completely different boat than you so I can absolutely say that it's impossible. Luckily, the Dems don't seem to have this problem. Isn't that strange? I don't need to use my imagination because I already know the answer. If there was a Dem that was accused of what Trump has been accused, AND CONVICTED OF, then there is no chance they would get my vote. Ever. For any reason. Ever.
Now... if the Dem candidate that you were presented with was someone you considered to be completely horrific and without a single moral bone in their body... would that prompt you to vote for a Republican? Would that single individual be so odious to you that you would entirely turn your back on the entirety of the Democratic party and vote for someone from a party that you are diametrically opposed to on nearly every policy position?
You're implying right now that if the Dem had the exact same candidate as Trump rise to the level of POTUS nominee, and the GOP had a rational, intelligent, experienced person with a down-to-Earth platform and the knowledge to know the difference between right and wrong, would I change parties? Yes. Absolutely. Without even a second thought. I would be so ◊◊◊◊◊◊◊ mortified that the people in my same political party would be insane enough to put a man like Trump as the head of my party that I would leave the party all together. I'd never go back.
You talk about expecting people to stand by their morals, and that's fine. What you're failing to consider is that for someone who is actually a conservative, actually a republican... standing by their morals means NOT VOTING FOR A DEMOCRAT.
And that's the ◊◊◊◊◊◊◊ pathetic part right there, that your values and morals as a Republican don't say "vote for who is best" they say "vote for Republicans no matter what". That actually explains a lot Emily's Cat, and you're finally coming around to admitting what you've been denying this whole time. You aren't a centrist, you're a Republican no matter who and that's your moral makeup.
I literally voted for Republicans 2 days ago. I voted for them for about 4 positions in my state because Dems don't have a great track record in North Dakota with parts of agriculture and some of the conservation projects. I do that because I believe it's what's best for my state and the people around me. The GOP I've voted for have a great track record in this state but people like our Governor, Secretary of State, etc. will never get my vote for any reason.
The best you can ask is that they vote for a third party or a write in candidate, or perhaps decline to vote at all. But you've repeated expressed that in your view third-party voters are just as bad as being a Trump supporter.
No, the best I can ask is that they have a little self respect, put their petty bull ◊◊◊◊ aside and think of the country and the damage Trump can do before they cast their vote. If they want to do like you and throw their vote away (though I'm not buying it), then that's fine to, or vote 3rd party. Whatever.
My views on 3rd party voting are that they are just a different way of supporting Trump, yes. That's correct. No one has to listen to me, and people rarely do. I also don't tell people how to vote. Little known thing about me but I drive people in my community to the polls if they need help. I do it every year, whether those people vote GOP or Dem, I don't even ask. It's none of my business.
Your position on this is irrational,
You definitely have that backwards.
and I very strongly suspect that you expect something from republicans and conservatives that you would never ever contemplate expecting from a fellow progressive or from yourself. You expect republicans to completely abandon all of their principles and values and turn coat to support a party that is in opposition to everything they believe. That's not just irrational, it's ridiculous.
That you view the Dem party as in opposition to all your values says everything anyone needs to know about your values. That you think the current Republican party represents your values says a lot about your values. I would absolutely expect myself or any progressive to vote for the more rational party. I already vote for rational Republicans in my state, there's no reason I wouldn't extend it further.