you are comparing JWism to mainstream religions whereas I see it as HARMFUL due to the way the WBTS has set itself up as an unquestionable authority ...
JWism is not the only religion that claims to be an unquestionable authority, is it? (And actually, if you go by the letter of what they write, which I'm sure a JW parent would introduce if forced to defend JWism, they explicitly claim not to be infallible). That is kind of the point, it's not a leap of logic to suggest that some people would be (and are) critical of mainstream religions, also. E.g., Islam is a religion of violence and extremism, Catholicism harbors a lot of child molesters (not my views, but suggesting what some argue). Plenty would argue that it's harmful to raise a child around evangelical / born again doctrines that teach that its ultra-conservative views are right and everyone else's are wrong. Maybe these are minority views, but you must recognize that so is yours. There are very few people outside of the ex-JW camp who are willing to broadly label JWism as harmful, but other religions as not harmful. I would be against setting a judge up to decide the rightness/wrongness of any religious doctrine, or to force a parent to raise their child the way s/he thinks is "best" unless the doctrine results in physical or emotional abuse, as legally recognized.
As much as I wouldn't want a child indoctrinated with WTS doctrine, when a family breaks up, it's never going to be ideal. I think looking at the individual parents and what's best for each individual child remains the best approach. As hard as it might be to swallow, it may not be better for the child's interests to be removed from a JW parent if in a given case, that also means being removed from many extended family members and being placed with a parent who is ill-equipped to be a full-time caregiver.