Okay, that's fair. But what if there weren't other options? If we used a parliamentary system in the US, and we were talking about voting for the Democrats or else a genuine leftist party, I would be 100% in agreement with you about voting for the left instead of the Democrats.
What if Germany used the FPTP system, and you were voting for Hindenburg or Hitler directly to lead the country? Do you think that someone in that hypothetical election who refused to vote for Hindenburg in 1932, because he hadn't done enough to earn the vote, would still feel justified in that decision in 1945?
I wouldn't be committing to voting for Hindenburg 7 months before casting a ballot, especially if doing so not only doesn't address the underlying problem that created the NSPD's popularity but would also likely continue to contribute to those conditions.
You're also assuming that Hindenburg would have won a second election against Hitler, and I don't think that's a given. Nor do I think Biden winning against Trump is a given either, when he's still contributing to the conditions that brought popularity to Trump. He's done quite a lot to undermine his own campaign message, and those of us telling him he's gon a loose if he doesn't reverse course are actually helping him, assuming he takes the opportunity he's being given.
Protesting biden now wouldn't be effective if we all -publicly- got in line and said "we'll sure, he's complicit in genocide but we're all still voting for him anyway". That would be quite a dumb way to protest and put pressure on him to get anything done, wouldn't you say?