I get your meaning but it feels overly reductive. I'd call good faith picking a catalog and not trying to prevent people from finding certain books "curation". I'd call "delete anything that says gay" censorship.

It's hard to have an objective standard. A curator and a censor are both trying to pick content they think is appropriate for their community.

There may be a difference in what they do when the community requests content not in the catalog. I would think most librarians would consider adding requested content or at least referring the patron to another library or other means to access it.

I think the point is that whoever is in charge of curation can (and likely sometimes do) quietly and easily delete anything that says gay without anyone really noticing

Then those same people will often make a fuss when someone else tells them what they are allowed to curate