As I have aged, I've learned to avoid certain situations.
People being cruel to others is never ok, but it is inevitable, especially in an anonymous setting. I would urge your friend to either grow thicker skin, or avoid streaming if he can't handle the type of degenerates who are known to frequent twitch. Him being autistic doesn't change the fact that there are bad, immature people out there.
Coming here and trying to appeal to the same community that contains the jerks you're lamenting won't change anything I've said.
Best of luck. I'm glad you guys were able to beat Oryx.