Damn, I really thought their set was cut short. I was on his side with this but oh well. At least he's getting treatment now.
This is kinda what happened. Lets say Usher was to perform from 9-930 and GD was going on from 945-1015. Usher went til about 950. Green Day took the stage at 10. They cut their set at 1015 because that was the time they had until. Can't blame the promoters. You can only blame Usher or the person who didn't alert Usher that he was over.