I have read the posts that say they have no sympathy for the kid and i think that is a little harsh.
I am terrible at online gaming so i only ever play Football/Soccer games. It is therefore rare that someone talks during the game, but on the off chance some guy talks when he scores. I just argue with him until he shuts up(guys like that are generally bullies, so if you talk back to them on the games, they don't really have much to come back with). So i feel there would be no need to track someone down and try and kill them. You could just turn down the sound or leave the game for a while