What happens in the scenario where the librarian is instead a low IQ worker helping out?
You: Can I have this book?
Worker: No, sorry, not allowed.
You: It's ok, the boss said so.
Worker: I don't think so.
You: We're friends, right? You don't say no to your friends, do you?
Worker: Well, ok, I guess you can have it.
Hey, the worker said it was ok, I guess you were authorized after all!
Sounds like you were authorized; if that happened and you read the book what crime would you be charged with? Seriously. Taking advantage of a worker with intent to learn secrets? Totally immoral, not illegal.