I agree that their methods are wrong as well as counterproductive.

because they see Trump and the right as such existential threats

I understand why they feel this way. Being a minority in any country means that you're never going to be 100% secure and safe, but just a few years ago it seemed like most people in the U.S. would have our backs. I genuinely thought a very large percentage of Republicans would vote against Trump because his blatant racism was unacceptable, but it turns out that it just wasn't important to them. It's not that that I think Trump or the current GOP are a real threat. But I could see how a Hitler-like figure could easily become president, and someone more competent than Trump could send us to concentration camps. As the percentage of Americans who aren't white increases and threatens to turn white people into a plurality instead of a majority, those on the far-right will become more and more desperate and willing to turn to violence.

I don't think it's correct, but it's easy to equate all Republicans to Nazis when your faith in the basic human decency of your ideological opponents and your fellow citizens is broken like it was during the election.