Your description of the failure to allow you to enforce the rules prior to the commie flu says to me that they really don’t give a flip about security, they just need a “security guard” to fill the checkbox somewhere, maybe so they can tell the insurance company they have one. Security theater instead of Actual security. (And how many actual library patrons did you have? I’m going to bet not many.)
As the commie flu panic calms down I predict they will slide back into their old habits of not wanting you to enforce anything lest you offend the homeless, or the clueless, or the latest alphabet identity.
So I am suggesting that you may want to reconsider your desire for a full-time position at the library in favor of a position that will have more appreciation for you and your skills.I realize it’s probably hard to let go of something that is already in your grasp, with the potential to go full-time and probably provide health insurance benefits and all that, but Since you are conscientious enough to engage in self improvement and try to understand the law, and explore the what-ifs, you are going to have some awfully frustrating days ahead I think.
And anything that goes wrong with “Security” will be your fault, whether it was too much or too little.
My two cents. Good luck.