I find it interesting you have a realitvely tolerant view of WBTS indoctrination material given your background.
I would say that it's not so much a tolerant view of WTBTS indoctrination as a desire to maintain a broader view of how child custody disputes should be best resolved in society. In trying to avoid tunnel vision by just looking at the consequences for JW parents, wouldn't this level of intrusion require a family judge to review all religious literature related to one parent's religion if the other has a problem with it?
Considering that family judges have a lot of discretion, wouldn't you be worried that some judge might have a bias against Muslims, Jews, Catholics, or some other religious group, and shape the custody order accordingly? I have a neighbor where the mother is a very strict Catholic, and her little girl believes bad people go to hell and homosexuality is evil. Personally, I don't think that's the best way to raise a child, but that doesn't mean I think the government should step in and tell her she can't do it.
Although courts do frequently make specific orders related to raising the child, I don't think they tend to tell parents what they can or cannot teach them, especially when it relates to reference to outside materials, and not activities specific to the parent. I thought that lost in the critique of the judge's decision was the concession that the mother wouldn't take the child in house-to-house ministry. I think that's a worthwhile step, because that can be quite damaging to some kids. Although it seems it was the result of an agreement, and not the judge's order, I believe at least in the U.S., it would be nearly unheard of for the non-JW spouse to be able to get such a concession.