I think the point is "We'd rather you left them where they were after you found them and notified a museum, so that they could be dug out with all due care by professional archeologists".
They've survived since the bronze age. They're not rotting away to dust any time soon.
What I thought when the British claimed they can stole things because they preserved it better. This thing have preserved in this land for centuries, and who's to say that British Museum won't get nuked in the next 100 years?
That’s not a particularly strong argument considering the state of some of the items in the British Museum.