Well of course they monitor these sites. That's one way they know they're being identified as a cult, and then react with a typically guilty conscience.
As for their warning about such sites endangering people's faith, well, if a person's faith is so weak that their hearts and minds can be changed by reading a few posts, then perhaps the JWs arguments aren't that convincing in the first place.
As stated elsewhere, cults attract a particular type of person. As people grow and evolve naturally, many outgrow the mental orientation that makes them vulnerable to the blandishments of a cult and they leave the JWs on their own accord. Same is true of people who were forcibly raised in a JW household. These people grow up, begin thinking for themselves, and reject the infantilism of the WTB&TS. That was the case with me.
The fear of the JWs to engage in public debate about their faith flys in the face of scriptural exhortations to always be ready to make your case for what you believe. Only cowards avoid such things.
Those boys in Brooklyn have been challenged to a debate right here on this board, and they're far too cowardly to respond - after all that foaming at the mouth they did in "JWs in the Divine Purpose." Now they're being hoisted on their own petard. Can't think of anyone who deserves it more. And the best they can do is issue their impotent threats that "Jehovah" is going to "get" all people like me, who call the WTB&TS exactly what it is: a damnable, dangerous, divisive, destructive CULT; and calling the GB what they are: knowing, deliberate LIARS (And by the way, Brooklyn Boys, God isn't going to do a damn thing about it.)