The term, hostile work environment, has a very specific meaning in employment law, and I would guess that about 90% of people who claim they are in one, aren't.
Do you know what he is claiming was "hostile"?
Two things I am tired of typing: 1.) A wrongful termination does not mean that you were fired for something you didn't do; it means that you were fired for a reason prohibited by law. 2.) The above answer, whatever it is, assumes that no legally binding contract or CBA expressly says otherwise. If it does, the terms of the contract apply.