"the non-autistic majority of us are well able to read the social and musical interactions in a session situation."

I've actually wondered about that, as a number of characters I've witnessed behaving in a distinctly self-focused / blinkered fashion definitely appeared to belong to some kind of spectrum of personality disorder, however mildly.

I've also encountered a higher quanity of that type of character at singarounds than almost anywhere, bar perhaps when volunteering for some charity drop-in morning, or on the bus (lots of kooky folks use the bus).