Why would he bother? If he's almost assuredly going to be one and done regardless of where his draft stock is, why not just prep the entire year and let teams draft you based on the mystery?
He's definitely not where everyone expected him to be as a prospect, but that upside is still freaky good. If he wanted to join second semester and then stay for a second year, he could be an All-American.
But if he's just going to show up, expect to join a rotation that's already established and cohesive, and bolt, I question how much he or the team he chooses would get out of the process. If you're Jahlil Okafor, that's one thing. If you're a raw prospect, it's a different animal.