We've decided collectively as a society that some ideas are "good" and others are "bad". For example, racism and white supremacy have been decided to be "bad".
There's an alternate reality where white supremacy is mainstream, where queer fiction is impossible to find, and that would be a different world.
Instead, what's being preserved are the books written that celebrate the values that match our broad cultural values, despite a handful of cultural deviants attempting to suppress the parts of the rest of humanity they dislike.
Sure. Just rename it to "Library of widely available and even mandatory for children to read books that we pretend are banned to preserve our image as underdogs, and excluding books that we've used our cultural dominance to ensure are actually hard to get."
It's a mouthful, but at least you'll be honest for once.