The authors of Oliphant's biography noted that "that was the prevailing attitude of almost the entire white population of Australia until well after World War II"
https://en.wikipedia.org/wiki/Mark_Oliphant
(Sydney here.) I've known two aborigines well, one was a dear friend for many years[0]. I'd have to say, and they would no doubt agree, that their whole culture–or whatever fragments of traditional culture they've inherited–"makes it difficult for [them] to adapt fully to the ways of the white man". Impossible to adapt very far or very well at all, let alone fully. Just as western culture, I imagine, would make it difficult for white people to "adapt fully to the ways" of aboriginal people if they tried, or to prosper in an aboriginal world, if it still existed. The whole "go to school, get a job, live in a house" thing was very foreign to my two friends, they had nothing of that in their lives. Aborigines didn't do that before white people came here, now that's what you have to do to be considered fully human, or to live decently in a city or town. Aboriginal culture was horribly assaulted for 150+ years, often with genocidal intent.. It's a huge tragic situation, with no easy answers. Australians no longer call it "adapt fully to the ways of the white man", it's just life in modern Australia, but it comes to the same thing.
p.s. Thanks to OP for posting this, I hadn't heard of Nicholls, sounds like an amazing guy and an amazing life.
[0] That was in the last 20 years, in Sydney. I grew up in the 80s in a country NSW town, lots of aborigines in the area, but I don't think I ever even talked with one. There were some at my high school but we never came in contact, at all. They lived in an aboriginal village separate from the main town; white people never went there.