since you feel you have overturned their belief system-what hope did you share with them?
I've never understood this line of reasoning.
If I walk past a burning movie theater, I have an obligation to warn everybody inside to get out.
I do not have an obligation to tell them the name of another theater where they can watch the end of the movie!
If a JW is unable to defend his beliefs, the onus is on him to research and find something to believe in that he can defend.