Opinion: Who was at Fault??

If you watched the race this past weekend you probably watched the fiasco between Tony Stewart, Carl Edwards and Clint Bowyer. If you did not see it I will set up the events. Clint Bowyer came off the corner with Tony on his outside and ran out of room, almost running Stewart into the wall (he brushed it). Tony retaliated by running into Bowyer sending him spinning into Edwards. Of course, this pretty much ruined the chances of Edwards and Bowyer making the chase. As you can imagine, Edwards was not happy with this, and made sure Stewart knew it. Later spinning Stewart on pit road (this was after Stewart gave Edwards the one finger salute). The fireworks continued after the race with all three sides sharing words. Now, who do you think was at fault for this situation, and was the penalty given to Stewart during the race stiff enough?