HBB said that those people might be irrational, but not insincere. They might be (or might not be) failing when it comes to weighing options rationally, but they're not failing in their sincerity. You said that even if both candidates were rapists, all things aren't equal; that's absolutely true, and I assumed (perhaps presumptuously) that you were acknowledging that as a sincere point of departure for some voters.
I miss the days when Dak would say something like "I assume you're playing devil's advocate" or "I assume you're adopting a difficult position."
If Biden were a rapist--i.e. admitted or convicted, or proven beyond reasonable doubt--I wouldn't vote for him. That shouldn't matter, because my personal opinions aren't what we're debating. You feel it necessary to make them the center of every discussion because your conclusions don't turn on facts or arguments, but on your perception of your opponent's character.
But as I said, I wouldn't vote for him if that were the case. The reason I plan to is that I'm not convinced he's a rapist, and because "#believewomen" means that Tara Reade has the right to have her accusations investigated, not taken as truth in and of themselves.