I was just in a few modded games of Halo 2 with this 12-year-old (by the sound of it) with the gamertag of XX KILL3R XX. As you can plainly see, he has not been banned from Halo 2 Matchmaking.
For some reason (possibly because of the flying tanks and rocket-shooting warthogs) only one game is showing up in Bungie’s records.
The game that shows up can be found below:
I don’t think that I would like to meet him in matchmaking.