So its your sons responsibility to always walk away from your daughters abuse simply because he is bigger? Why isn't it your daughters responsibility to learn not to antagonize your son? Shes only 9, but he's only 13, and possibly dealing with pressure from your ex from what you wrote earlier.
It doesn't seem to send a good message that you want to put all the weight of this on your sons shoulders simply because he has a penis.
That'd how it seems to me.
But im probably misunderstanding it so i'll leave it there I think. Um tired and confused!
ETA and before anybody jumps up my behind, no I am not saying that women who antagonize men deserve to be hit or any variation on that theme.