The sub having a child with autism is probably hyper-aware of potential 'issues' in other children. This can be a double-edged sword. On the one hand, it will likely serve some children well- there are so many parents out there whose children HAVE issues that are constantly chalked up as 'behavioral' when they are tied into serious medical problems and getting the school system to acknowledge this often leaves these parents ready to bash their heads against the wall. On the other hand, though, kids are often just being... kids, and that is MOST OFTEN what is going on when there are problems and once parents know about it they can address it with their kids. The more experience she gains, the more discernment she'll develop there. But overall having that experience w/ a special needs child will serve her well as a teacher, I think.
I'm glad the OT will work with him re. pencil grip and handwriting. This will lay a good foundation for cursive, which usually comes along in 3rd grade- and strong writing skills/technique will be important to have in place to do well with that. Poor pencil grip will also lead to hand fatigue down the road and may make him resistant to writing for longer periods... not so much an issue in the earliest grades but writing assignments get longer the older they get, etc.