There is apparently somewhat of a history between Greinke and Quentin but Quentin, who gets hit by more pitches than anyone, also has a history of acting like a tough guy towards the pitchers when it happens. IMO it doesn't matter what Greinke said to him, he shouldn't have charged the mound. I know if I were a pitcher and hit someone, intentionally or not, I'd say something if he was giving a hard looking and walking toward me.
They won't be able to suspend him too long because their isn't a precedent to do so, but they need to start a new precedent for situations like this. If you charge the mound and players get hurt the punishment should be more severe.