Autistics aren't naturally wonderful people because of their disability. In any disadvantaged group, there will be people who seek reassurance from evidence that others lumped with them into the same category are "worse" than they, for example "I'm autistic but still I have a girlfriend whereas no woman would ever be attracted to HIM with that constant stimming etc.". It's like you might even have a gay man who takes pride in not "talking like a <gay man>" or an Asian man who boasts of his sexual prowess, to differentiate himself from Asian men who are stereotyped as being bad sex partners for women. That sort of behavior has always existed. The problem with SM is how it's allowed the world to witness this behavior as a form of entertainment, and revealed humans as being the sh!ts they are.