You must withdraw your name by May 30th to return to college and be eligible.wait, what ??? no. if a player is not drafted how is a team gonna "call him up". There is no policy or rule in the NBA that would affect this its 100% NCAA letting them keep their amateur status.
There is one case of a player going thru the draft, not getting picked, and returning to school. Randolph Morris at UK did it after the 2004-05 season. I recall they made him sit out the first half of the season and he basically returned for SEC play. He was considered a free agent by the NBA and signed with the Knicks a year later. I can't remember if they found some loophole that has since been closed or what, but you know the NCAA bends over backwards for its breadwinners. That's why the UNC academic fraud has just disappeared like a fart in the wind. Basically I'm saying UT basketball doesn't have that kind of clout to get Bone back. He gone.