Interesting, I was not aware of such a cannibalistic culture before.
The idea of not caring or revering the bones of another culture is not unique to NZ. The Navajo, a large indigenous group here in the US, had few qualms about excavating Chaco Canyon, the residence of a previous culture, including bones. They would even attend occasional fiestas there.
And today jar tombs are excavated by the thousands and the rare textiles sold, whilst the boes are scattered about, or even made tourist attractions in Peru, particulalry Nazca tombs.
I am not defending what happened, just adding some perspective from this side of the world.
I think at times people carved what they SAW.

Anyway here is the link I was thinking about...
http://www.celticnz.co.nz/SurveyorsNZ/Ancient New Zealand Surveyors.htm