I also agree that the smartest thing is to disallow any minors from my game. It is the simplest move that solves all problems. In fact, since the other kid's mom (the lead whisperer in the whisper campaign) has gone pyscho, there is one regular player who is a minor.
But I have to look at that kid and ask, "Does he or does he not deserve to play?" My gut says yes. I'm not doing anything wrong, I'm providing a social, intellectually stimulating and creative activity. I have as much right to teach the game to a younger generation as anyone, and he has the right to play it.