It is an interesting theory, if I understand it. Is the Idea that controlling a geographic region makes one the rightful heir to any artifacts created by people and cultures previously in the region?
Does the USA have a claim to all indigenous Artifacts created in the US? It doesn't seem that different than Egypt laying claim to Egyptian artifacts.
I think it’s clear the spirit of my comment was to mean that the descendants of the original owners would be one of the parties with a claim to have their artefacts repatriated. It’s clearly not a strictly geographical problem.