Are you, or the parent, a mental health professional? If not, then I'd suggest you aren't qualified to tell if he's even autistic at all, or, if he is, that his autism is what's causing the problems here, not terrible beliefs, behaviors, and attitudes. In that light, using autism as an excuse for Stallman's behavior is just an unfounded theory by an armchair psychiatrist with no business making diagnoses.

As a neuro-typical, it is an insult on me. Being autistic doesn't mean you are allowed to be an asshole.