I think Coelecanth said most everything that needs to be said. However, under both L75B and L20 F5(b), the player must call the director first and then inform the opponents. I did not see in the scenario as described that the director was called until the conclusion of play. If the director had been called at the end of the auction, he/she could have allowed the NOS's final pass to be withdrawn. Not knowing what everyone else held, the NOS may not have changed their last call, but they may have doubled, which may be as good as equity and may be the adjustment that the TD would offer. Even if they declined to change their call at that point, since the damage occurred earlier in the auction and cannot be corrected under L21B1(a), the TD could award an adjusted score unde L21B3.