I certainly can't speak for Vassar, but why on earth would he transfer?.
Because he likes to play basketball?
Something happened at NU such that he is no longer on the team. It would not be at all hard to imagine he would like to continue to play competitive basketball, even if he (like >99% of other college ballers) doesn't have a future in the NBA!
Whatever happens, I hope he gets a decent college degree, hopefully from NU.