I agree with OG that you should chill out, but I also understand where you are coming from. Unfortunately we have seen more than one case on this forum where a parent completely bowed out of the children's lives when their new significant other was legally restrained from being around the children.
Basically dad is going to eventually get tired of the restriction...and several different things could happen. He could get smart and get rid of the girlfriend, he could ignore the order and have the child around the girlfriend and tell the child to lie, or he could bow out of the child's life, maybe temporarily, maybe long term. (depending on how long the girlfriend lasts)