[mikst]

First, you should find out exactly what is happening. Coroborate what he is saying.

Assuming things are as you say, fist thing is to teach fear management. Do light fear training. Nothing extreme, ideally something tailored to his psyche. Without this nothing is gonna work.

Then, teach him crowd control. I'm not joking. There is science on how to deal with a crowd. You don't need to explain advantages of Android, but how to use them to stand up to those kids.

Both of these skills are universally useful, and will help him in life almost guaranteed.