It's an interesting (and scary/depressing) subject to think about - what proportion of people would or wouldn't find that acceptable in even more extreme circumstance?
Let's imagine a hypothetical political party and its presidential nominee that had an official policy of "if we get elected, we will nuke every country in the world except our own, and if we don't get destroyed in return we'll then move on to use our military to murder every white person in America" (hopefully that's extreme enough and far enough from actual policies for anyone to read it as a dig against a particular party!), and imagine 51% of the country supported this party and these policies. How many people would go "well fair enough, democracy!"?
It's a bit like that old line attributed to Churchill:
> Churchill: "Madam, would you sleep with me for five million pounds?"
> Socialite: "My goodness, Mr. Churchill... Well, I suppose... we would have to discuss terms, of course... "
> Churchill: "Would you sleep with me for five pounds?"
> Socialite: "Mr. Churchill, what kind of woman do you think I am?!"
> Churchill: "Madam, we've already established that. Now we are haggling about the price"
It's easy (for some people, though I don't condone this view) to look down on prostitutes as being immoral and disgusting if nobody would offer you more than £5, but how many people with that view would be willing to bend their ethics if they genuinely had an offer of tens of millions in return for having sex one time?
Likewise, it's easy to say we should respect democracy when both sides genuinely want what's best for as many people as possible but disagree on how to achieve that, but what about if democratic voting leads to having a leader like Stalin, or Idi Amin, or Putin?
Put another way: if you sincerely believe either that all Democrats are evil and trying to wipe out white people and destroy Christianity, or you believe that Republicans are all literally the same as Hitler and will do as much harm, in either case (despite neither view being accurate) if it's a genuine belief then isn't the ethical reaction to oppose them even if undemocratic? (As a non-American I can't claim
to be an expert on what the worst, most-exaggerated claims made against each of Biden and Trump are, so insert whatever they are to replace the examples above.)
One problem is when you get leaders who genuinely will do evil things and yet manage to be popular enough to win elections; the second problem is when you have enough people believing conspiracy theories and bad faith claims about a party that make them look evil. Neither is an easy problem to solve.