"Secondly, in my experience and others I've read - autistic individuals seem to often do much better at understanding each other. I mean this in two ways: autists are often better at understanding other autists than they are at understanding neurotypicals, but also in many cases autists may be better at understanding other autists than neurotypicals are at understanding autists."

This is an interesting point.

"With this framing you could just as well say neurotypicals lack a theory of mind. Largely we don't do that because there are more neurotypicals than autists."

I think the really interesting result would result from testing this.

i.e. because of prior knowledge, neurotypicals model the default person as neurotypical.

However, knowing whether the second party is neurotypical or autistic, can a neurotypical person model their second party's mental states better than an autist, or worse?