I'm aware of stories of people who've had their flights unexpectedly grounded in New York (, New York) so they just abandoned their checked pistol and refused to collect it. I'd imagine something similar. If you never take possession, it becomes harder to charge and convict someone for possession.
But wouldn't they know whose bag it was anyway? And there's cameras everywhere so it wouldn't help if you e.g. removed the bag tags or discarded the contents somewhere else in the airport.
