Well, there are very legitimate, obvious cases where in the course of the game a pitcher accidentally hits a batter. There are zero legitimate cases in which a batter charges the mound. None.
I'd be open to the situation you described, as long as it can be determined with reasonable certainty that the pitcher was throwing at the batter. But in the case in question, it was a 3-2 pitch against a leadoff hitter who has been hit more frequently than any batter in MLB history. There's roughly a 0% chance Greinke was trying to hurt Quentin. There's roughly a 100% chance the reverse is true.