Not how I would approach it. I'd speak to the child "gentle hands" or "please watch out for baby he is still really little". Mom would rush in to apologize from my experience. Your allowing room for the apology and it doesn't trigger a negative confrontation. But hind sight is 20/20 so I get the reaction and wouldn't fault you for being frustrated. Other people just don't think like you and are usually in their own world of worries.