Comment by sfink

You may be overthinking this. "Banned" in this case means that the usual person or people who choose what books to include are being overridden by a party with more clout. From the perspective of a school librarian, for example, book X has been banned. They no longer have the option of including it. (This is even true in the case where the librarian would not have included it anyway, for their own reasons.) They are prevented by the school board, an angry mob of parents, the state legislature, the FBI, or whoever. The fact that the public library down the road carries the book does not change whether that librarian has the option of including it in their school library's collection. They can't. They are banned from including it.