It's clear to me that this kid shouldn't have been playing CoD, based on the fact that he's too fucking stupid to understand "This purchase will cost $19.99. Confirm?"
I mean, weather children should be precluded from M-Rated games completely is rather more dependant on the kid and the parent's understanding of the kid. I mean, my dad is an attentive parent who closely monitors my younger (13) brother's activities, but he allows CoD simply because he's familiar enough with the games, and with my brother, to know that it's not an issue. I mean, for his age, my brother's a smart, mature kid, and he knows how to segment reality from fiction. However, we would NEVER allow him to play CoD online. We know better than that.
Off on a tangent there, but my point is that this asshole, and yes I mean the father, is completely irresponsible. You need to monitor what your younger kids are doing in games, especially online. But no! Don't worry! If it doesn't go well, you can just blame the company that made the game/console! Why not! All they did is design and patent a piece of entertainment, then slap a huge, unmistakable letter on the front telling you age restrictions.
Those bastards.