It seems that most are advising you to drop it and safeguard your friendship.
I'd like to suggest that you consider the following. If you were the active JW, you'd have likely responded in a similar fashion. You'd have felt threatened. After all, the society says that apostate thinking is designed to tear down your faith.
This is all about approach. If you approach it in the correct way, you will not lose the communication. Simply say that you certainly will accept this persons faith and opinions, and you will never use "apostate" sources, rather you will use the society's literature and the bible as the basis for your questions. Make sure that everything you say is something they can check in the bible or the society's literature, and don't use the UN or other "worldly" examples...at least not for a long time.
If I was the active JW and you helped me see sense I'd thank you for it afterwards, a hundred times over.
Close down communication on this issue and you run the risk of this person never getting the information that he/she may need to change their life for the better. Continue the communication and you run the risk of losing the friendship...if you do things too agressively. Its a difficult choice but I know which one I'd take.
Overall, I wouldn't want a friend who censored me.
Sirona