Huh, I have to say that this was far more civil than I was expecting (and I'm very pleased by that). And it's true, this is a complicated issue and there is nuance to it. But she did not say that and I can tell you (as someone with experience in this regard) that that was not her intent either. Here's what I know:

The argument is that the idea that Indigenous Peoples migrated from Asia 15,000 years ago is a theory steeped in the colonial mindset, is contradicted by volumes of evidence, and completely ignores Indigenous narratives and sources on the issue.

And, as she was alleging, it's used constantly to deny Indigenous identities and sovereignty. And that agenda is obvious, it's tantamount to saying "you didn't originate here!" Whereas no one questions European identity or claims "they came from Africa, so its okay we took their land."

Modern evidence, which is far more consistent with said narratives and sources, indicates that the migration occurred much earlier during a previous glacial period - ca. 40,000 years ago. This includes genetic evidence obtained from tombs in South America dating back to more 25,000 years ago and oral traditions that speak of the encroachment of glaciers.

But what is especially frustrating for people such as th author, is how people reared on the Bering Land Hypothesis and other Eurocentric theories feel fit to "explain" to Indigenous People where they come from. That's about as "whitesplaining" as exists today.