I think that's really just a poor excuse for plundering. I attended a lecture in Chicago, delivered by a British Museum curator, about the 'Elgin Marbles', i.e. the large bas-relief scuptures that the British had removed from the Parthenon and taken to England. I talked to him afterward, and said that I was aware of the preservation motivation, but wanted to know if any thought had been given to idea of restoring them to the Parthenon, perhaps subject to an agreement by which the Greek government would safeguard them against deterioration. After trotting out some paternalistic disingenuities about what's best for the Marbles, his final reply to me was a loud and contemptuous "It's booty; you don't give back booty". That seemed more honest to me.