In no way does this excuse his assault on the child but you know this guy was probably subjected to the same. I’m not one of those nuts who says spanking a kid is child abuse, but parents don’t seem to have any common sense these days when it comes to being parents.
Spanking a kid, more so for what he did and at this age would be about 4 or 5 swats on the butt, not beating the hell out of him like you would someone who said shit to you at the local bar.
Yes that boy was old enough to know better and deserved a spanking, but he also deserved from his real dad or mom who would do it in a loving way and not nearly kill him.