I don't quite agree. Setting the minimum standard for insurance is regulation. I've looked closely at the law and certainly Quaker Colleges end up paying taxes that support the Defense Department. (Your argument.) There's a case to be made that the regulation was targeted at the Catholic Church. On other grounds, religious liberty (America's First Freedom) is already at risk under an opinion written by Scalia that largely leaves religious relief from facially neutral regulations to Congress, hence the importance of exemption clauses. Worry about the likely success of the Bishops before the Courts, but not because the "preventive care services" are a tax but because the level of scrutiny of facially neutral rules is very low.