> Prominent liberals like Alan Dershowitz
While at least notionally a Democrat (and one who claims to be a liberal one) Dershowitz is to the right of even the mainstream of the dominant corporatist neoliberal faction of the Democratic Party. And sometimes quite far to the Right, such as his eager advocacy for (not defense of something already being done, but advocacy for a new and novel policy) a systematic and public policy of specific collective punishment by Israel against the Palestinian population in violation of international humanitarian law, or his proposal for "torture warrants" in the early 2000s.
> say they're being socially blacklisted for not taking part in a pile on against Trump
Dershowitz has been one of the right-wing's favorite "liberal Democrats" for a lot longer than the Trump Administration, and has been marginalized by the left of center and increasingly the Democratic mainstream for that from the early 2000s, even before the accusations that he wasn't just Epstein's lawyer, but also a significant client, and his recent campaign against the ACLU.
He's not been marginalized just because he hasn't taken part is a "pile on" against Trump.