PhDs are now being purged like teachers, librarians, state workers, etc.

Protections under the first amendment, which restricts government control over speaking out on matters of public interest, under most conditions.

They are free from any form of retribution.

I am a retired tenured full professor from a top US university and this happens to be within of my field of expertise. You need to read up on “employment at will” and the “public sector exception” to it. It is a separate issue from academic freedom. Public universities and colleges generally cannot fire even untenured faculty because of their exercising free speech rights (private schools often can, because the first amendment speaks only of government, not private, restrictions on speech).

Look up the fairly recent Indiana University case re: an economics professor who articulated racist and sexist views.

And the public sector exception to employment at will?

I am also a PhD from a top university, but only lowly adjunct faculty, so you know more about this.

You may find them interesting.

Faculty with contracts (union or individual) or tenure that includes academic freedom may have additional protections, etc., but here, the faculty member probably doesn’t have those. But he has Constitutional rights (within some limitations). I hope he wins.

There are also multiple campuses including more that are planned. Students that want to pursue a more rigorous academic pathway are more likely to attend UT-Dallas or University of North Texas in Denton.