A private book store could say no since they are a private company....subject to the state's anti-discrimination laws. I don't think there us much the city could do since it is a public library. Even if they were to, these events could then be hosted at these pedos, I mean trannys, homes.

The city can't say no to adult content from performing in their public forums : https://casetext.com/case/se-promotions-ltd-v-city-of-atlanta-ga

Nor can they outright ban them just because there might be youths present: https://supreme.justia.com/cases/federal/us/352/380/#tab-opinion-1941379

see also sable communications v fcc.
https://supreme.justia.com/cases/federal/us/492/115/#tab-opinion-1958067

About the best they could do is a time manner or place restriction, and to design it in such a way that it doesn't become a prior restraint nor content based discrimination, with events marketed at children-And background checks are a must in such events. Even the pennywise jokes could get the city in trouble if they were to prohibit the speakers on that basis.

By all means protest and educate parents about what depravity goes on in these places as you are doing. The fitness of the parents who bring their kids to these events ought to be questioned and doubted. Be mindful of the Streisand effect.