I also find it Authoritarian for Private Christian Schools, who are continually bleating for Federal Cash Infusions, in the shape of School Voucher Schemes, to think they have the obligation to dictate off campus behavior of Non-Students.
BTW, Does this school normally Spy on Parents of their Students? Or was this just such an extreme case that Pastor Busy Body and his Merry band of Web Surfers just couldn't resist the urge to pry, purely for Inquisitorial reasons, or course?
Reminds me of a local Mennonite church that excommunicated one of it's members because a fellow member of the congregation saw him at the Pizza Hut, drinking a beer with his pizza. True story.