Depending on whose definition you use, he may have a point. It’s well understood that Maori came from elsewhere to NZ, and quite recently in historical terms. Thus, are not “naturally occurring”.
Of course, they did get here first though, and we signed a treaty guaranteeing certain rights regardless.
Mostly this is just Winnie being Winnie.
I mean, Homo Sapiens is only “naturally occuring” in Africa. We may have spread to Asia, Europe, Australia and the Americas (much) earlier than to NZ.
But if you think of the Maori as a people of Oceanian (more specifically east polynesian) descent, you can absolutely make an argument, that they are a native group spreading in their native territory.
You wouldn’t call a north american native people “not native”, just because they began settling some remote part of Canada nobody had been to before only in 1250 CE. The only difference would be that one is separated by water while the other is not, but “separated by water” loses all meaning in Oceania.
