It's even worse then if he had the wrong skin color because at least that's real. He has been lynched because of straight up lies by the media.

When a mob lynches someone it's obvious they "had enough" of him. And maybe he even was guilty enough to deserve such a punishment. But we hardly ever think about this, to us a lynched person is always a victim. Why? Because nobody can be so guilty as to deny them a due process. A real justice where the person can face the accusers and defend himself, and be sure that the decision is made by a jury of impartial peers. People who "finally had enough" can only be the accusers in this scene. Where are the others?

Do you really think that insensitivity and vulgarity is worse than mob justice?

A lot of lynchings took place not just because the person had the wrong skin color or other immutable trait. Often the victim was seen as uppity or acting out. I think the parallel holds.

Edit to add: Some people have said that Stallman is nuroatypical. If that is the case then it could be very well that his actions and comments are from a trait beyond his control.