>he Austrian government claimed that a safe return would be impossible without a specially designed case to protect it from the vibrations caused by flight.

The damage argument seems pretty self-serving. Even if there was damage during the flight, how much would happen and how much couldn't be repaired? I suspect anything done on a flight could be restored just fine.

There's definitely a ship of theseus aspect with artifacts. I imagine most of things of this class have been worked over many times. Adding another layer of damage and restoration to bring it back to its rightful home seems like a reasonable price.