the fact that it was his kid and he was disciplining him makes it different, it just does. I'm not saying I would ever discipline a child that way, or that discipline at some point isn't abuse. But assuming there was indeed an intent to discipline (as opposed to merely injure), it's a different situation for me.
Parents have a duty to discipline their children and both custom and the current law allow them substantial discretion in determining how best to do so, and allow them the use of physical force (which is legal in all 50 states). It makes it a different situation than Rice's.