The notion that Biden represents a lesser evil compared to the chaotic reign of Trump is a common argument. However, we must not forget that there exists a moral threshold below which neither choice is acceptable. To suggest that enabling a literal genocide can be considered a lesser evil is a morally bankrupt stance.
Saying that voting for Biden is a moral obligation to prevent the return of Trump perpetuates a dangerous fallacy. It implies that the democratic party is immune from scrutiny and accountability, no matter the atrocities they commit. This line of thinking allows for a never-ending cycle of justification, as long as there's somebody considered worse, the democrats are granted a blank check. This is nothing more than a form of gaslighting, manipulating the public into believing that their only choice is between two evils, rather than demanding a better standard of leadership and true representation.
You can do that. You can do that by voting third party or abstaining. As i tried to explain to you, these are also choices. These are also levers that you can pull, you are not forced to choose between pulling the red or the blue lever. Choosing such a third option has the beneficial effect of decreasing the legitimacy of the duopoly. The more people that choose to do this, the less believable the claim will be of whoever wins having a "democratic mandate".
Further, as i have repeatedly tried to explain to you, it is not clear which if any of the two tracks that you think you have to pick from is actually the lesser evil. You axiomatically assume that you know which of those two tracks is less harmful, but you don't.