You weren't really friends, he was a freshman, you were a senior.
Sounds VERY MUCH to me like he's trolling for phone sex partners trying to friend any possible female he can think of and then screening them immediately for vulnerability. This is the same pattern I encountered on dating websites, very familiar. I smell predator from here.
Don't ignore your intuitions and the red flags. You owe this man nothing. Unfriend him and stop communication.
