He said something he thought to be true - he was making a rhetorical point, in an uncomfortable and insensitive manner. He doesn't really come from a position of power and notably, has wasn't 'going after' anyone, just making a dumb comment.
The person representing the authority or power in the equation ... it doesn't matter much what their statements were, the fact is they went after him (and others) in a systematic and authoritarian manner.
At most, he should have been asked to apologize for being insensitive.
The school, however, needs to be investigated for systematic oppression of profs. using their weird internal investigations to harass people (aka '9 hour interviews? That's fing STASI like stuff, it's what the FBI does to serial killers. Could you imagine your employer grilling you in a room for 9 hours?).
He spoke out of line, the school acted with retribution using arbitrary authority.