If there was an official rule, then there would be a legal case for Anti Trust against the Big Ten. That was the bases the NIT had against the NCAA tourney. The NCAA said Texas Tech could not turn down an invitation to play in the NCAA tourney just to play in the NIT. The NIT brought legal...
You can say Gatens was a Lick recruit & be correct, but every coach the Hawkeye's have had would have recruited and signed him. While he may not be the complete answer, he is not the major problem either, IMHO.