That being said I try to live by the principle that attacking somone's beliefs is assault but concealing the facts from someone requesting or needing them is deception.
PP, While I let my JW family members be, it is only because coming out has to be on their own terms.
First of all, they actually don't have beliefs beyond "Watchtower is always right." The vast majority of JW's do not have their own beliefs that the flood really happened so long after the actual banishment from the Garden of Eden. They don't have a belief that a creator of the universe hates blood transfusions and birthday cakes and clinking glasses at a wedding reception. So revealing information contrary to "Watchtower is always right" is valuable for people in a dangerous mind-control condition.
Secondly, there are ways to reveal such information without "attacking." I now always encourage independent thinking on the part of my JW loved ones.
Otherwise, I really agree with what you said.