I don’t think time is the important factor. If the U.S. today was the same U.S. 300 years ago, then we would 100% have a moral obligation to shut that shit down.
Now there is a diverse population, a culturally rich melting pot. However the U.S. is still plagued with racists/bigots, problematic entities, and a corrupt government.
Anyone who believes in any sort of racial supremacy, born in the US or not, should get kicked the fuck out.
Any problematic entities, such as oil companies ruining this land, should be dealt with. If Native Americans start biting back because their way of life is getting fucked especially, then they have my full support.
U.S. government is rife with corruption which spreads through many sectors ranging from health care to law enforcement. If Native Americans somehow overthrew the current government and replaced it with something more democratic, representative, or something just better, people would not have a logical reason to complain.
TL;DR
Time is irrelevant. The U.S. is no longer full of cunts, but the ones that do exist should GTFO.