I think it’s difficult to say, however: My speech therapist once told me that when parents come to them with a stuttering child they usally recommend not doing anything about it (unless it makes things like school or making friends difficult) because like you said it could make the child self couscious about it. A lot of kids ourgrow their stutter, so waiting a few years might be a good option. As a kid I was was very shy and self conscious about my stutter, so my parents decided to take me to a speech therapist. This was because I had a lot trouble with it. But it kinda made me more anxtious about it too, making me stutter more. It’s a real paradox. If your step son likes reading out loud, this is a sign he doesn’t worry about it, which is good.