I've come across this article before, and like all the other ones I've found that talk about a "Moriori myth" they seem to be creating and attacking a strawman:

I've come across this article before, and like all the other ones I've found that talk about a "Moriori myth" they seem to be creating and attacking a strawman: principally, the idea that the Moriori were the first inhabitants of New Zealand proper, rather than the Chatham Islands. That (incorrect) claim is nowhere in the original post here, or the Wikipedia page on the Moriori, but by knocking it down vigorously and then quickly eliding over the details of the genocide ("...yes, some Māori did kill some Moriori...but to attribute this to all Māori is wrong, and if you find yourself wanting to do it you should question your motives in doing so", which reads as another strawman: who is blaming ALL Maori?) the impression is given to casual readers that the historiography is wrong and the genocide never happened.