JW: Well, look: I go door to door every week. I hear all sorts of arguments from all kind of religion. If any of them could show something jw believed in was not in the bible, I think i would have heard it by now.
The Witness here is not saying that it is wrong to consider what critics and apostates have to say, but unnecessary since any legitimate criticisms would turn up in conversation while out in field service.
Ask this person outright whether or not they personally would read material (apostate or otherwise) that was critical of Jehovah's Witnesses.
I suspect that they would not. In that case ask them if this is how they make other decisions.
If they went to the local Ford dealership would they trust a salesman that told them, "The new Mustang is great. Don't read the review in Consumer Reports though. It's all lies and half-truths. Just take my word for it and buy it now."?
Or what would they think if they had a rare illness and their doctor said, "I have a new experimental procedure that can cure you. Other doctors think it's dangerous, but they're all quacks and liars. The entire medical establishment is corrupt. Whatever you do don't get a second opinion."
I think in both of these situations and many others Witnesses would tend to think more critically and view claims of exclusivity with suspicion. They need to apply this same type of thinking to their religious beliefs as well.