Hope he likes Europe
That's the real thing here -- it has nothing to do with the draft. He's not being drafted. It's whether or not he gets the right feedback from NBA teams and thinks he can go to Europe (like White) to work on those holes in his game. If he thinks he can fix those holes, while getting paid, he's most likely not coming back.
He may be getting advice that there's nothing else for him to achieve coming back to Iowa City and that he'd have been luck honing and refining his game in Europe. If he thinks that's a better spring board than a senior season, that's the case for Europe.