Wow, you guys get spun up over the littlest things.
The UN has not decided anything. Nor will they.
1. The Declaration on the Rights of Indigenous Peoples is not a legally binding resolution.
2. Nothing in the 46 articles indicates in any way that a country would ever have to give anything back. There is an article for reparations, but that is only for land taken illegally. Since the US writes the laws, most of what we did to the Indians was legal.
3. Not to doubt the Daily Mail, but according to the UN website, the reports of Mr. S. James Anaya don't mention Mt Rushmore. BTW the Daily Mail could not even get his name right.
What Mr. Anaya is saying about the US is the same he is saying about other countries "you guys really need to improve the way you preserve indigenous cultures. "
In other words, nothing to see here folks.