Thomas Sowell has already destroyed this argument. These "banned" books can be bought in any bookstore. They will be happy to order it for you if they do not have a copy in stock.
When the left says that a book is banned, what they mean is that some annointed elites in education choose a book for school and parents objected and overruled them. More generally, what they are saying is that parents should not have a say in educating their children. Leave it to the annointed (and the government).
The issue is not about 'banning' the novel, it's about whether or not it should be REQUIRED reading or even RECOMMENDED reading (presumably it would be one or the other, probably the former, if it's included on the syllabus of an AP course). Leftist trash always gets into a lather about any attempt to review a syllabus, yet they would never accept that all the good/great conservative books are 'banned' if they are not included on some course syllabus.