Treat stimmy behaviors like ordinary fidgeting. They are only weird relative to a framework that an autistic does not operate within. Specifically, they do not say anything in particular about whether he is paying attention, especially to a person who he wouldn't be likely to make eye contact with anyway.

Sidenote: This applies to us ADHD kids too. Fidgeting is how we make our brains work. It is self-medication. Now, if one kid making their brain work is making 29 other brains not work (ie by making distracting noises) you obviously have a problem. But that problem should be solved with a view to helping us find harmless ways to fidget, not making us stop fidgeting entirely.

Data point: I'm 27, work at a tech startup, and would've had a much harder time staying alert in a meeting today if I hadn't been turning an hourglass over in my hand and watching the patterns the sand made.

Citation: http://adhdmomma.com/2011/12/guest-post-fidgeting-helps-kids-stay.html http://phys.org/news162554898.html