USC had no choice to enter him into the portal. They have to if it is requested. You may be thinking of the old days, "Permission to Transfer" model. Since the portal days began they go by a "Notification of Transfer" model. The player TELLS them he/she is transferring, the school cannot stop him from being able to be contacted by other schools.
The one-time model EXCEPTION doesn't care about whether or not a prior waiver was made. That said, you could put it in your packet and hope they consider that in the WAIVER.