I didn't say bringing lawsuit against anyone. The lawyer advises how to approach the university, possibly approaches the university themself, and monitors how things are developing.

What you say highlights an aspect of the risk and harm to grad students that I didn't articulate, but is implicit in my suggestions of how to approach this. (And there's also a related aspect of "damaged goods" that a wise person told me about: even if it was clear that the student was totally in the right, the mere fact that they got burned by someone else suggests they might have lingering problems from the stress, and people would prefer a bright-eyed clean slate student.)

You need the right level of the university to know they have to take you seriously and cannot just neutralize you. And preferably before other university people compound the problem with "coverup is worse than the crime", creating more reason to cover up.

Approach this game-theoretic, and make it in everyone's best interests for the university to do the right thing, early -- before the underhanded and the arrogant scattered throughout positions of influence in the university do what they would do otherwise, and make the problem much harder to fix.