I’ll end with this, since I know I’m being longwinded.
If this is something he ends up doing, you’re going to have to let go a little bit and trust the process. The Marine Corps trains thousands of new Marines a year. They won’t break him. Yes, he’ll probably be hungry. Yes, he’ll be tired. Yes, there will be moments when he thinks “Why the hell did I do this?!” Most people going through basic training are having the exact same thoughts.
Then, when it’s over, they look back on it with a lot of pride, they’re glad they did it, and they’re eager to start their military service. The things that were so scary a few months ago now seem funny, and they’ll laugh about basic training with their friends. It’s just part of the process. It happens to everyone. They’re going to push him to his limits, but they’re not going to take it so far that he’s actually seriously hurt.
I’ll bet you five bucks that if he enlists, he’ll go through basic training thinking “This sucks, I shouldn’t have joined” and then after he’ll have a newfound sense of confidence and be ready to go to his unit as a new Marine.
Just my two cents. Like I said, if you have any questions feel free to ask.