Agree with others and will add... a big problem with being pigeon-holed as 1B is that this is where colleges look to play others who hit well but aren't good enough defensively to put elsewhere. That is a group that is typically fairly crowded at most programs.
If ability allows, he is much better off as a prospect C or 3B and versatility adds to his value. That said, if he mashes, someone will find a spot for him and it could very well end up being 1B so he could certainly benefit from getting reps there.