Its called fleeing you dumb fuck! And any one around has a right to stop him from fleeing. Did you not notice the prep then put up his fists towards Roger? Of course you didn't. That gave Roger the right to defend himself.The guy who hit the girl was twenty feet away from her when he was confronted by the vigilante. He was clearly no longer a threat to the girl. The attack by the vigilante was illegal for a number of reasons.
Read the law, a person may use force to stop a felon who just committed a crime from fleeing!