There will always be people who  believe in fringe theories for a variety of reasons. As we learn more about the early polynesian migrants to NZ  at places like Wairau Bar,the more we find similarities with Moriori. Early "Maori " in NZ also showed no tendency towards a culture based on warriors and warfare as happened in NZ and the North Island especially, from about 1500. It seems that a variety of events happened in the South Island about 1450ish which drove Maori to migrate-some to the North Island and some to the Chathams. We are finding out more about the "1450" events every year. An underlying cause may have been climate change. Other likely causes were earthquakes and Tsunamis. As mainly coastal dwelling people, without any scientific understanding of random natural events, it must have been terrifying to live on the Otago coast then given that many food sources-especially Moa had been hunted to extinction. Anyone who could survive on the Otago coast in 1450 could survive on the Chathams.