I am currently doing speech therapy, and I’ve found it incredibly helpful, particularly group therapy. It not only works on fluency but also the emotional aspect if stuttering. From what you’ve said, I think therapy would be highly beneficial. After around 10 weeks, I’ve noticed some significant improvement. It’s a slow process that requires tremendous time commitment, but I believe it can work if you put the effort in. There are no shortcuts. Just a note: make sure he goes to a stuttering therapist, not just any SLP.