Be Wise,
I think your approach was good. Even though we don't realize it when we are young, negative thoughts are what we hate!!!! Positive thoughts are what we love!!! When we are in a JW family, as a young person, we don't realize the negative effect on us, since it is not contrasting to anything else. The org. makes certain that there is no comparison!!!!
Don't make any drastic attempts to save your nephew, but continue with POSITIVE, KIND encouragement. I'm not big on a god figure myself, but believe very strongly that TRUE, GENUINE GOOD DEEDS are rewarded, and I'm certain yours will be.
Brad