No, the accurate statement is "This specific online search by Daniel P.B. Smith on this specific date did not return any results". And, of course, there's no guarantee that 1 minute after Daniel P.B. Smith does his search, the book will not be acquired, or entered into the catalog, or re-indexed properly because it had been improperly entered before, or...
There's no guarantee, but if someone tries the search a minute later and gets a different result, and it's not from some transient glitch, they can edit the claim or remove it.
Databases, library catalogues, and similar ephemera are complex beasts that have little in common with printed works.
There's no guarantee that two different physical copies of the same printed work have the same contents, either. I can tell you from personal experience that there are in existence copies of songbooks published by SPEBSQSA that have identical titles, paginations, copyright dates, credits for the arrangements, etc, yet have significant differences in the notes on the page. We usually find it out when the chorus starts singing and different guys in the same section are singing different things. If you ordered it in 1990, you got a different arrangement than if you ordered the "identical" book in 1980. Someone at the Society thought it was OK to correct or improve the arrangements without any indication that anything had changed.
I don't believe for a minute that this is the only example of that in the world.
It's highly _likely_ that it wouldn't be true of a book by a respectable publisher--they'd bump the number of the printing or something. It's also highly likely that two queries to an electronic library catalog, a minute apart, will yield the same results