http://en.wikipedia.org/wiki/Straw_man
Isn't using this Biblical account to make their point about the dangers of apostates an example of a "Strawman" argument. They seem to have oversimplified one side of an issue to prove a previously held point.
They assume that those who were slaughtered for their offences against God in this Biblical example are equal to anyone who dares to question the Watchtower Society today. You don't even have to be a Baal Worshiper....simply walk away from the organization and you are equated to someone in the Bible who was worthy of being slaughtered for his offenses toward God. How is this even provable? Yet many will sit in the WT study not really paying attention and buy into the whole notion and start applying it to some family member or former friend.