Bullying triggered my stutter, but I have never been bullied because of it. My parents talked to the teacher, and they made sure I was still respectful to everyone. It sucks to stand out. I don't really have good advice about this. But I wanted to give some general advice. Please don't make his stutter a big thing in daily life. Be patient, and make sure he isn't afraid to talk to strangers either. Or to talk at school etc. My parents just pushed me to do the same stuff like every other non stuttering person does, and I feel like I am miles ahead of other people thanks to that. I also didn't ask for special treatment besides extra time to give presentations, I just did them and I still do at uni. It can be exhausting sometimes to talk, but yeah, it is just a thing you have to deal with sometimes. And I went to speech therapy for improvement, but mostly for acceptance. The second part is very important. This can boost your self esteem a lot, if you don't see it as a huge burden in your life.