If he is being excluded from participation in teams and clubs based on the fact that the application process is not accessible to him due to his disability, and he has been denied requested reasonable accommodations (such as a scribe or an alternate format application) in the application process, the school is in violation of the ADA.Just sayin'...
You might want to check out other local community groups and resources, like 4H
I think that Aculady's point here is very important. Hopefully soon your son will have documentation for his disability, and then it can be pointed out, tactfully, that it just isn't fair to have a timed element to the application. Soon also, your son will be keyboarding, and that may very likely open the door to more of his amazing richness of ideas being visible.
For now, I think that groups like 4H, which stress process over product are the way to go. Our kids want recognition. Competition is about the only way our culture can figure out how to give recognition. Some kids have contributions to make that are totally unique and could not be judged better or worse than anyone else's because there is no one else in their catagory. Keep you eyes open to those sorts of opportunities - things that involve creativity and beauty. Some people get inspired from product - completions, awards, etc. Other people get inspired from process - the ingenuity of the solve, the beauty of the materials. Both are good, Both are needed. Both ways have advantages and disadvantages.
Best Wishes,
Grinity
