Well, not really, but there had to have been a reason…

One of the more unusual uses I’ve seen of a baggage stamp. The tying cancel appears to be the norm, based upon other examples of the stamp I’ve seen, so no reason to believe it is contrived.

It surely can’t have been typical, otherwise we would see more examples… I wonder what the rationale was.

Speculation from another collector:

Perhaps the book fell out of someone’s bag or luggage, or it was left on a seat in a departure lounge, and turned in to lost and found. As it likely belonged to one of the travelers, a well-meaning customs officer stamped it on the front so as to be noticeable, ensuring that it would be considered to be a passenger’s property, hopefully to be claimed on-board or at the destination.