As far as I understand - world was generally nuked into Long Night by asteroid in this version, somewhere around 1000 BC. That's quite plausible to nuke most Eurasian powers.
Bit like this setting I've once read about when Black Plague killed 99% of Europeans, and Asian powers recolonized Europe.
You could have santa claus kill every last white person, and it wouldn't have made America sufficiently rich in certain resources required to produce a sufficiently advanced civilization, nor the kind of groundwork of concepts required to create a society that has concepts of the Rights of Man, the Scientific Method, or the Universality of God. You aren't going to get there when you're having huge trouble getting around to inventing the wheel.
It is a complete fantasy based out of a wish fulfillment that utopia would have happened were it not for the evil white men, when in fact it was Western Civilization that has, in all of human history, gotten as close to Utopia as anyone has so far (though admittedly still very very far from it). It's resentment pseudo-history.
The most likely outcome of no Columbian Exchange would have been that in 2021, tribes would still roam the great plains killing buffalo and each other, while central America would be at some stage of its seemingly eternal cycle of building up monument-building empires based on human sacrifice and then having those empires collapse from resource-scarcity back into primitive tribes based on human sacrifice. Maybe the Inca would have fared a bit better, but it's not too likely.