Ant's version of NZ Maori history is the politically sanitized version, where any references to pre-Maori has been removed, making it easier for the dominant tribes of Aotearoa to lay claim to all that belonged to other sub-tribes or hapus that had been dominated, including their oral history and whakapapa, which is also regarded as taonga (treasure).
The real history of pre-Maori NZ is yet to be told, officially, although you can read about it by searching for 'pre-Maori NZ', just google, there are several researchers and authors on the subject.
Change the flag by losing the union Jack and NZ will start on the road to becoming a republic. Once a republic, that'll be the end of the Maori cash-cow, the Treaty of Waitangi, then no amount of sanitizing the books will help advance Maori, the opposite will become true as Maori will start to claim back the suppressed history of the land,....a mighty story.