That is taking PC to absurd extremes. Now we must allow primitive savages' ignorance to drive scientific inquiry?
Whether they were too ignorant to find out about migrations or not, clearly they are newcomers. It will be clearly proven that Kennewick man predates all "native" Americans by a whole bunch.
PC.... R.I.P.
I say, at least 3,000 years and probably much more. Arlington Springs Woman has been dated to 13,000BP. (The oldest human skeleton ever found in the Americas)