I don't support what this guy did. It was wrong. But some of these kids with online gaming can't shutup.
When I do online gaming, I personally set my headset mic to "friends only" so only my friends I'm online with will hear me. Even my own team I'm with won't hear me. Just friends.
These kids make it so everyone in that game session hears what they say and bad mouth as they play. It annoys the shit out of gamers though, and a lot of the time people leave that game session and join another where people play normally.