Sorry, I haven't been nor have I read any reviews of experiences of teens with special needs. We haven't had much at all reported here on the disABILITIES Forum about Aulani in general. It does not appear that there is a "teen" club, only for ages 3-12. The website does mention a teen spa (Painted Sky) that is also described as a "teen hangout" and appears to include a lounge and computer stations in addition to spa services. I don't know if that area might be of interest to your son to find some friends. You might try posting over on the DVC forum to see if anyone there has experience. Please report back after your vacation to share what you've learned and done.
Enjoy your vacation!