Actually, it's not despite the T&C's, but because of the T&C's. Setting aside the issue of using someone else's card, the requirement for the FHR program is that the person on the reservation has a Platinum or Centurion card and uses any Amex card to pay for the stay. I would imagine that the hotel presumes that the Platinum or Centurion requirement is met if the reservation was made by PTS/CTS, so all they need to do is make sure that you use an Amex card of any type to pay for the room.