I don't believe the article is denying the schools' right and responsibilities in protecting children from harm. It is just assuming as much as commonly accepte

I don't believe the article is denying the schools' right and responsibilities in protecting children from harm. It is just assuming as much as commonly accepted. Then, it does the same with regards to the "harmfulness" of these books. Or, more specifically, it names some books (Beloved etc) as well as concepts (health education) in a way that assumes its audience will tend to agree that these aren't harmful to children. That it doesn't necessarily extend that belief to all books is clear from the distinction it makes when it separates some books from others that have been "caught up in this net [such as] books about health education, teen pregnancy, civics, philosophy, religion,..."