Your premise is absurd and as usual pro-homosexual.
The homosexual materials are abnormal --WHY should anyone be used to homosexual materials in school in the first place. "Parents" use to such materials are the exception and probably homosexuals first and parents second. Negative reaction homosexual materials is a normal reaction to the abnormal; ESPECIALLY, when specifically we discuss a 6 or 7 year old child being exposed to such garbage that you yourself imply normal to get use to...
Apparently the reaction of other parents in the school to Parker's antics would seem to belie that statement. You seem to forget that this is Massachusetts. Homosexuality is treated differently there than in most states. So anyone moving there for the first time would no doubt for the first time be introduced to the materials.