Doubting Bro: How do the grandparents have any rights at all in this case?
By acknowledging that the rights of the child and the child's guardian have precedent over the grandparents' perceived rights.
The grandparents in this case still have visitation rights. However, because of their past performances that disregarded the right of the parent to control the child's religious training and upbringing, those visitation rights have been curtailed. Now, those visitations will be limited to one hour per week in a supervised environment.
The grandparents' rights are superceded by their responsibilities. And, their primary responsibilty is to respect the rights of the parent and child. And to provide a conflict free, safe environment for the child. The grandparents gave up their rights when they put their own rights ahead of the rights of the child.