The story seems to read that the biker had become friends with the aggressive car drivers ex-girlfriend, now I wonder if there was a ulterior motive behind that attack.
Plus you don't know the person riding around on your (stolen) bike hasn't just bought it and infact is an innocent party.There was a case a few years ago of a guy walking home after going out to buy tea/wine etc. Car stopped beside him, "offenders" got out and tried to steal his wallet plus drink etc etc.He was a Black belt in some martial art, overpowered them plus infact broke one of their arms. THEY sued him for damaged caused and they won compensation (from his own pocket)!