Their core mission is to lobby for federal funding for library services. In that role they are certainly open to public commentary on their decisions.
Ideas that are then are reflected by the member libraries across the nation. It’s more complicated and complex. It’s not the local Elks club. They have power of persuasion over thousands of educators and public institutions.
And the criticism isn’t around censorship. That’s the popular conflation here on this thread. It’s about political and social opinion of an elite class determining what is or is not appropriate within their world view. And in many instances it obviously ok. Like the civil war statues. In this case I simply believe it’s gross over reach.