If he does well in workouts I think he should go into the draft.
Also, an argument could be made that he would be better off signing a 1 yr deal in Europe with an organization that has a track record of developing big men for the NBA. Then he could enter the draft the following year with film of him playing against much better competition than he would at BYU---along with having bball be a full time job to get his skills and body developed.
If I were him I'd choose NBA 1, Europe 2, college 3.
There are a lot of misconceptions about playing in Europe. It is high level bball and some teams have a bunch of guys making over 1m