I haven't read this whole thread, but as a college professor (whose office is in the middle of a dorm) I can tell you that condoms are readily available on college campuses. RAs at my institution keep a basket of them outside their doors, they're given out at hall meetings, and the student health center has them as well. There are many, many ways to get them without having to ask, buy, or having it be known that the student got them.
I'd say the main thing to do is keep the lines of communication open, so that a) he knows that he needs to use them, b) he understands consent and everything around it, and c) he feels like he can talk to you if something happens or he has questions. So many of my students use their peers for advice, and they get BAD advice from their peers!