Biden's hands are kind of tied. There is no evidence that Trump consulted with him before issuing the order, and the optics of cancelling the protection for Trump's kids and then having something happen to one of them isn't something he's going to want hung on him. Better to let it go, give them the six months protection, and move on from there.
Sorry Doodle we were talking about Biden swimming nude in front of his female SS. I should have highlighted the conversation.
You are right though, if Biden cancelled it he would have to accept the consequences