Could well depend on the state. Non-competes (which is effectively what an anti-transfer clause in a contract is) are largely unenforceable in California. And absent a contract, the courts have already ruled that NCAA anti-transfer restrictions violate antitrust.Yes it is. Contracts do not run afoul of antitrust laws.
You didn't believe me on this issue around the Tez Walker case, but the judicial writing is on the wall now. In the absence of collective bargaining, Claudia Wilkens is going to be ruling for the players for the foreseeable future.