I agree with parakeet. Though, I know it would make me feel better to plant a few seeds of doubt, I would much rather do this with an adult. That 10 year old has years of living with his JW parents and what can he do now if he did have doubts? Nothing.
If someone approached my 10 year old and said something to them about how great the Witnesses are and would he like a pamphlet, I'd want to hunt them down and beat them. It goes both ways.
Those comments are better said to adults.