Serious answer, probably because books from book stores aren't available to the poorest classes. Libraries are (and are meant to be!) a threat to every status quo.
This is specifically a school library, not a public library. And no, I do not support book-banning in any way, shape, or form. Just keeping the facts straight.
To support the idea that it is class based, I suspect we will find it is being selectively applied to poorer communities, which specifically drives the most able-to-change-jobs (often the best) librarians to move to other communities where this is not being applied.
If you don't think that Republicans are interested in an all-out assault on libraries in general, I kindly suggest you check a book out about it from your local library (while you still can).
Because this is a boil-the-frog situation. The path is k-12 school libraries -> public libraries -> academic libraries and bookstores. The way fascists get the public comfortable with the idea of banning books is by starting with examples that look like "common sense" to the uninformed, and then ramp up the attacks as they gain institutional power.