In spite of his permit, he is not mature enough to be carrying. Either he has not had any safety training our he is totally disregarding it. Either way, he is going to hurt someone. These are not toys and he is not cool.
As far as asking him nicely, it's not about making him feel good about himself. It's about handling a firearm in a safe manner. If he were in the Marines and he handled a firearm that way, his DI would stomp the living bleep out of him.
His attitude stinks. I think he's taking advantage of you.
This is probably the most severe criticism you're gonna hear on your post. I'm sorry but that's how I feel about it.