Books that are assigned reading in schools and universities, and promoted by libraries, are "under threat", while books nearly impossible to find, never on any reading lists, and whose promoters get their speeches shut down by French police [1], or get investigated by the FBI and kicked out of university [2], are to be considered widely available, got it.

And your "historically banned" is just "occasionally removed from public school libraries on parental request". Not using tax money to promote them to children is a low, low bar for "banned". While actual availability is, of course, completely ignored. Whatever tells the best story, facts be damned.

[1] Jared Taylor's Banned Conference Speech - https://www.arktosjournal.com/p/jared-taylors-banned-confere...

[2] Ohio universities involve FBI in investigation of ‘It’s okay to be white’ and white nationalist group’s postings on campus - https://www.thefire.org/news/ohio-universities-involve-fbi-i...