But is it reasonable for someone to be essentially fired for having an incorrect opinion?
Whether or not this case crosses it there clearly is a line where expressing an opinion isn't okay. If he was spouting off racist stuff you would have very few people defending him being fired.
Yes. There are laws against workplace harassment. Harassment may include repeated voicing of discriminatory opinions. The harasser may be fired to prevent the workplace from being a 'hostile environment'.
Even when the law does not require action, someone may be fired even after a single conversation with incorrect opinions (and I mean 'incorrect' in the factual sense here). Take Jimmy Snyder, a.k.a. "Jimmy the Greek". https://en.wikipedia.org/wiki/Jimmy_Snyder_(sports_commentat... .
> On January 16, 1988, Snyder was fired by the CBS network (where he had been a regular on NFL Today since 1976) after making several questionable comments about African Americans during a lunchtime interview on January 15, 1988 with Ed Hotaling ...
More directly, if it's the 1950s and I call my stridently anti-Soviet Union boss "a pinko Commie" to his face, that's voicing an incorrect opinion -- and I might easily be fired for it. (It's not hard to come up with modern-day examples, but I felt it best to use phrases which no longer have the emotional power they once did.)
None of these apply to what happened with Stallman. I instead wanted to address your broader topic of being fired for expressing an opinion.
That’s the point. If it were harassment, false accusation of a colleague, etc, it would not be merely expressing a bad opinion. But as you say, none of those apply.
And I think it’s clear I was not raising an issue of what is legal, but of what is right and just, and desirable for a university, for a workplace, for a society.
But you asked a much broader question.
I gave two examples, one real ("Jimmy the Greek"), and one hypothetical ("pinko Commie"). Do you really want to get into a discussion of how it was not "right and just" to fire Jimmy the Greek for his racist comments?