It's actually categorically false that PSL does this, in fact the controversy that you'd likely heard about Stephen Powers was specifically spread widely because of the sexual assault being investigated and found not to have occurred, but him still being permanently suspended from the party because he allowed a messy social situation become a focal point for right wing slander. As someone's who had to deal with their genuinely frustrating and horrifying share of SA and Sexual Harassmet in "radical" communities, the internal systems set up in PSL genuinely are pretty much everything I could want.

Inside of PSL there's a national council made up of nonpartisan SA Survivors who address things on a case by case basis. The reality is that when you start to grow people in a space, SA can happen, it's only whether an organization admits it and addresses it that affects whether it's actually dealt with or swept under the rug. If you're pretending it's not happening in your groups, it's simply because you're sweeping it under the rug or your group isn't large enough; it's something that happens and needs to be addressed. "Critiquing" PSL because it taking the steps to deal with SA and Harassment has exposed that it happens is unserious.

Edit: Also I think the Marcy thing is just a historical thing? As far as I know everyone is MLs, it's certainly been the basis of decision making that I've interacted with anyway.