After your post about meeting his parents I agree with Checkswecks, he wants to be part of something. However, I think he won't admit it. He is trying to be self dependant and not need to depend on anyone.
If it was me, next time I see the kid I would apologize for calling him on the carpet in front of his parent. He needed to be called on the carpet, the apology is to build a mentor/student conversation. I would explain, his situation is a lot like a drunk driver to me. Friends don't let friends get behind the wheel drunk. Not only for their safety, but the safety of others also. Often someone who has been drinking will argue they are fine, it was only three beers, I don't need you to drive me home, and so on. With any luck the kid will understand this as driving while impaired may have been beaten into his head in school and on TV. I would then explain automobile drivers that have a tendency to go fast in their automobiles tend to go even faster on motorcycles. They argue I don't need to slow down, they can handle it, they are going to be safe, and so on. The auto driver is often impaired by alcohol or drugs, the motorcycle rider is impaired by adrenalin.
Often the rider does not even need to be on the bike for the adrenalin to kick in. Just thinking about a fast ride on a nice road will get the blood pumping. How many of us still get on our FJRs after owning for a year or more and still find we get excited, happy, and the blood starts flowing, and we are still in the driveway.
I would also let him explain why it upset him. This will allow me to understand why he is shutting down to advice. Maybe, I could prevent pushing one of his buttons and keep him open to suggestions.
I would then use the videos I mentioned in my first post.