You've taken a strong position, but one that I believe is fundamentally wrong. Is there any point in making a stand against Trump when the groundswell support for Trump is so high? Aside from getting a morality boner, you'd get ousted and replaced by someone who genuinely believes the rubbish that Trump spouts and is far more dangerous.

The Republicans have tied their fate to Trumpism and it's going to be interesting to watch what happens next. I think what you're characterising as moral cowardice, is more likely to be political expediency. The second impeachment was a non-starter, and grandstanding that wasn't thought through. It felt like justice, but it was a waste of time. It was always going to be better to let lawyers tie up Trump for his criminal acts after the fact than have that fight.

And centrist Republican senators know that, getting themselves booted out of office and replaced by Trump friendly lunatics would've caused chaos. It may have been honourable, but it'd also be stupid. They've got 4 years to try and move the demos back to the centre ground, into some sort of collective de-programming and back to reality. They need to emerge into a centrist party without splitting themselves in two. Working with Biden might help legislation start moving and cool people off but they're walking a tightrope. You might not like it, but that's politics. Always the long game.