I'm open to hearing other rationales, but none come to mind in making more sense than the above theory.
If I were one of the parents, I'd be livid, if I wasn't informed of precisely what the kids were going to be exposed to. It's not the school's job/responsibility/anything to facilitate the kids to form opinions attitidues of what they should believe. They're there to teach reading, writing, math, science, arts, and physical education. All else is the domain of the parents. Except of course to the elitists who think they simply know better