I often see this phrase and it looks like a fallacy to me. Does anyone question its validity? Social consequences are a severe thing, in practice they mean losing a job or position, boycotting, etc. In ancient Greece to expel a person was a very strong punishment. Nowadays the associated hardbacks are milder perhaps, but still are pretty severe.
If speech is so potent a weapon that to protect against it we have to use extreme social defenses like expulsion, why not to use the same weapon against the perpetrators? Why not to speak in return? Stallman says something, you say something. Take that, Richard Stallman!
I would say that the only appropriate social consequence of free speech could be other free speech.
Also, a distinct characteristic of a true community is that it's inclusive. It can expel its members, but this has to be a very rare event, only when that person's action are actually destroying the community. "Creepy and inappropriate behavior" that went along for many years is hardly that. It's a mere personality quirk. [Addition] And I'd say that this expulsion endangers the community much more than whatever Stallman was inappropriately doing all these years.