Curtis is "chop/chop/chop" on taking the order & giving the order to his men. He wouldn't have been focused on anything but bringing the operation off on the dime. Not a good time to be reflecting on how maybe Jack is using the old Flank 2 code...IMVHO, of course!
Curtis was there under the old code. The decision to abort or not listen to a hostage under duress or do the opposite would be major for an assault team leader. He would have known what Jack was saying. But the writers were going for Sean's character to make a splash.