It's been awhile since I've researched this, but isn't the teaching that the only ones who don't get resurrected are those that commit the "unforgivable sin" . Of course, in their mind blasphemy against the Holy Spirit = rejecting the WT. The definition I found on the JW website is that the unforgivable sin is working against the Holy Spirit accompanied by a bad attitude. The examples are Judas and the Jewish religious leaders that had Jesus killed. By extension, you could say apostates or anyone that works against JWs are also doing that but as long as they are still alive, they can "repent" by changing their minds.
That's how they get around the problem of the question TD asked. Because if you "know" JWs are right and don't do anything about it, then you will have committed the unforgivable sin and have no resurrection hope.
I think for some people, that teaching makes people stay even more than the shunning of family. I think may that leave but still sort of believe must torture themselves with "what if they are right" types of questions.