This is true, I am sure in your conception of what ethical behavior should look like but just as a liberally logical person would naturally conclude that a profoundly dishonest person would lie at the drop of a hat, so to would such a person take into account the historical fate of women who reported rape against powerful men. For ever and ever and still to this day requires tremendous courage to face the heat such men can bring to bear to destroy their reputations. It becomes part of the standard repertoire for legal defense teams to bring that up at trials which is why evidence that the aggrieved woman told close associates at the time of the rape that become vital parts of evidence. The same thing holds true for liberally logical people when dealing with pathological liars. No logical person will ever trust anything people like that say. Your problem, if I can call it that, your unconsciously assumed bias, goes first, not to the logic of the situation that raped women don't like to speak about being raped or that liars will naturally lie, but to the evil that is done by people who bear false witness against others.
You are so biased in that direction, a very principled moral value I agree, but in your case in my opinion, it clouds our vision to what is even more obvious, that liars lie and rapist rape and trump was so convicted in a court of law. Your moral values that it is wrong to accuse people of crimes without evidence will not be lost by looking at a spectrum of evidence. That will remain wrong because it is a valid moral principle. It is just that there are other moral considerations to be had also.
It is wrong to protect a guilty person from overwhelming evidence of guilt if you are biased in what you call evidence. Trump was convicted and accused of many more crimes than those. There is massive evidence he is a hugely unprincipled liar and an all around asshole to boot. You can't be rational and vote for him. Whatever emotional pain facing that takes you should face it. I say this as a person who lost everything I held dear to the principle I held to the most, merciless honesty. Before that I did not know that all my sacred cows were a prison, one that I could not see.