real talk? okay then
autistic people tend to fixate on things more than regular people do. That's why there are more autistic people in fandoms anywhere, whether that be sonic, other games, anime, furry/brony, etc etc... because they fixate on that thing more than normal people do.
There's nothing inherit about sonic itself that draws autistics towards it, it's just in inherit property of fandoms in general, whether you like a given fandom or not there's guaranteed to be more autistic people in it than the general population