Several years ago, I was in Pompeii taking incredible photos of everything I found interesting. I came into an area where I found three Amphora wine vessels leaning up against a wall. Once I got my photo, I walked out and was confronted by the tour guide. He told me that I was in an area that was restricted because of the sensitive nature of ancient structures. Back then, they were afraid that the traffic of tourists would destroy the roadway through the ruins. I think, if they were so careful back then, they must be just as careful now.
Without much to go on I’d guess that sounds like a shakedown opportunity by the tour guide. I’ve read about antiquities being returned to Pompeii by old retired tourists nearing dead, or by their heirs, carried right on off the site and onto a boat or train and home. Great that they were returned, but A) no one knows where they came from, B) no one at the site ever seems to have missed the item (else it would be simple to put it back, and C) probably means a small bribe made it all possible.