The issue is not voicing an opinion in private -- it's voicing it on an institutional mailing list in his capacity as a member of that institution.
Deciding post-facto smells of favoritism and can never be proven to be fair. It also creates a chilling effect since nobody ever knows what is and is not ok to say, since at any point in time AFTER the fact you might decide it is not ok.
I'm almost certain MIT has an employee handbook that reasonably covers situations like this. If anything, it's a demonstration of favoritism that he wasn't fired in the past.
The beauty of REAL freedom of speech (like we had in 1977 [1]) is that the answer to that is: none
[1] https://en.wikipedia.org/wiki/National_Socialist_Party_of_Am...
Because if i can lose my job over a statement and a mob reaction, the mob makes me unemployable since they scare other employers, i lose my livelihood, and thus my life. If I have no protection from that (enshrined in a law, like california actually has), in what way is speech free? It becomes more of: "speech only as authorized by the mob-du-jour".
That they feel they cannot take on the burden of RMS's stupid comments in addition to their existing scandelous items is not surprising, and should not surprise anyone.
RMS may well have gotten away with making the comments he did, had he been posting on the UCB mailing list.
Everyone is allowed to believe anything they damn well please. They are even allowed to state it. There should not be a viewpoint holding which makes one unemployable. because as soon as that exists, there is no freedom of speech, only a caricature of it.
freedom of speech is not about saying things that everyone agrees with. It is about saying things everyone disagrees with. and yes, speech comes with consequences. But those should be doled out logically, not by an angry mob forcing an institution's hand.
The common argument that I hear is that free speech does not come free of consequences. Fine. But those should be clear and well defined. Not decided by a mob at any given moment. If you want to clearly state that you will not employ anyone who holds the following views, that is okay with me. But firing somebody because the mob demanded it, is against the very idea of freedom of speech