It's important to realize how difficult it is for some young high school kids to step into this new role of semi-adult. For many, it's easy enough. For others, though, it's extremely difficult. It takes some preparation and some experience. Don't get me wrong, they are going to have to learn - and learn fast - to take care of themselves. It took a LOT of coaxing to get my kid to make his first recruiting call to a college coach. He did not want to do it. Over a short amount of time, though, he's gotten more comfortable with it. It was a matter of him finally understanding that this was something we could not do for him.
So, don't be surprised if your kid talks to the coach and doesn't do the best job of expressing what needs to be said. I don't think it would be out of line, in this situation, after your son has approached the coach, to follow up with a conversation that just confirms that the kid did talk to the coach and express your concerns that he was able to express himself well.