Is it the Chief Justice that determines what cases the court accepts and rejects? I thought it was a vote by the justices that determined that...although I certainly could be wrong.
As for this decision, I agree that if join an organization then you agree to abide by its rules. I believe that next term, the SCOTUS will hear where the school involved is not a member of the sport association involved, but that association is attempting to enforce its recruitment rules against that school. The association's reasoning is that the school is within the association's geographical jurisdiction and so is bound by the association's recruitment rules.