This sort of situation is exactly why I think "Ok" should be banned from the Magic lexicon.
As a judge, I want to look for what "Ok" has meant previously in the match. How have similar situations been handled? If previously in the match, "Ok" had meant "That resolves" then they're sunk. Otherwise, it's a judgment call.
If "Ok" was used in the same scenario all game long, would that suffice as evidence that a priority pass had been made? How would a judge evaluate what "Ok" previously meant in the match?