First, "lynch mob" is inappropriate and irrelevant. Given Stallman's statements, in the forum in which they were made, many reasonable employers would have fired him, with or without some "lynch mob."

Second, Stallman didn't express his views in private conversation, but rather in a forum where those views would have made it very hard for colleagues to continue working with him. If I'm X and you tell me or to Y in private conversation, "X is an idiot" or something of the sort, then that's one thing. If you say so in a forum where others can read it, then you're showing public disrespect towards colleagues, which is a fireable offense.

Here's what he could have said instead: "Have we seen evidence that Minsky himself engaged in illegal activity?" That's it. It would have expressed his point just as well, and would not have shown disrespect toward colleagues.