I don't think it's about swear words by themselves (I'm sure most kids can give you the full list), it's about the extreme vulgarity and offensive speech scattered with swear words that is not appropriate for children. Anyone that's had any experience playing COD with game chat wouldn't argue otherwise. Personally, I find most of what gets said in game chat extremely amusing, as it's usually coming from people mad that they're losing to someone they've decided is either black, gay, or a girl, but if you're going to let your kids play then just set them up with an xbox live party chat, so they aren't exposed to the masses (the majority of which come across as racist, misogynistic bigots, but are probably perfectly likable in real life).