Lets go with deceit.
So is asking for book ISBN '1; DROP TABLE books; --' deceitful? Perhaps, that's not an ISBN after all. Is asking for book ISBN [some valid ISBN that you pulled out of your ass, but happens to exist] deceitful? I don't think so. If you are just asking for randomly chosen ISBNs and getting responses, I don't think there is any trickery involved.
In one case you are counting on the system to correctly understand your (validly constructed) request, in the other case you are counting on the system to misinterpret your request in a dangerous fashion.
If I hand the librarian a piece of paper with that SQL-injecting ISBN my culpability depends on whether I was aware of the likely gravity of my actions or whether e.g. I was told to get that piece of paper by a trusted source (e.g. my supervisor) and didn't even read it.
What you (the asker/trickster) think the askee thought of it.
400 BAD REQUEST
Whomever staffed that librarian, should interview or train their staff better.
