Sounds like me when I was 14, honestly! If he's well-adjusted and doesn't feel like stuttering greatly affects his life, then that sounds fine to me. I stopped speech therapy right around the time I got to high school, it just didn't seem like I was getting anything out of it anymore. If something changes later on and he feels like he wants to try speech therapy again he can, but he's at an age where he has the wherewithal to decide that for himself.