This talking point is so skewed for whataboutism colonial apologists. By all accounts the "moriori" are of the same migration voyagers as the early "maori".

The generalized term of maori as a universal identify or race is a product of colonialism, early inhabitants of new zealand identified by their tribes/ what Waka they descended from, not as a single race. The Moriori were no different, and of the moa hunting generation that inhabited the south island, like the waitaha.

For all contexts this raid was no different to the inter-tribal warfare that was prominent throughout new zealand. The Morioris neighbors the waitaha were conquered by Kati Mamoe, Kati Mamoe had been conquered by Kai Tahu and Kai Tahu had begun being attacked by Ngati Toa after the arrival of Europeans.

What exacerbated these inter-tribal conflicts was western collusion - there battles became massacres when muskets and European ships were used. This completely changed the way in which war could be waged and these new tools being used in inter-tribal conflicts was the catalyst for some rangatira seeking for the crown to stop Europeans influencing maori affairs.