1) Video games are not linked to violence. The science shows this clearly.
One study even showed there is less violence after a game is released, presumably because people who'd be out committing crimes are instead preoccupied.
2) Come on, people are responsible and mature. They can handle a few pixels on a screen.
3) It's probably not even this. There are probably drugs or something in some obscure corner inside the game which is setting them off.