Kuvult:
1. Public libraries in general have long preferred opening on Saturday and closing on Sunday, even in neighborhoods with large Shomer Shabbos populations. Compare the Saturday hours to the Sunday hours. And as a consequence, they are unable to accommodate staff members who are unwilling to work on Saturday.
2. These biases go way back. Over a century ago, New York State’s librarian was fired at the insistence of the legislature since he was openly anti-Semitic – and the library profession was outraged by the legislature’s bias. Job discrimination even against non-frum Jews continued through the mid-20th century, and even today it is hard for someone who is openly Orthodox (Shomer Shabbos, and whose clothing and preferred days off based on the Jewish calendar) to get a job as a librarian unless working for a Jewish library or as a specialist in Jewish/Hebrew studies.
3. The people running NYPL are left wing Democrats, as is most of the city government. The new “politically correct” position is that all Jews (not just religious ones, though we are the most visible) are public enemies who should be discriminated against. What we would want is for advocates of “Diversity, Equity and Inclusion” to be seen as what they are, Nazis if 21st dress and treated accordingly (fired and marginalized) but the reality is that they control most of the political institutes in blue cities and states.