Thanks for your comment. 

As per my post above, the uproar was about non-indigenous people attempting to write about indigenous people. 

But suppose a non-indigenous writer decides to write a story with indigenous characters? 

Is that permitted, or is that 'voice appropriation'? 

Or do you have to look at the result and determine whether or not the writer has written something worthwhile? If it is this, okay there isn't much debate because you are judging the 'work' without having to resort to looking at 'who the author is'. 

However an editor wrote an editorial suggesting 'white' writers 'stretch' (learn) themselves to write about 'what they don't know'. There was an immediate uproar that he was advocating 'voice appropriation' (i.e. 'whites' shouldn't be attempting to write about indigenous peoples  since they can never know what it is truly like) and he had to resign. 

The meaning of this seems to be that 'White' writers shouldn't be writing about indigenous culture.

QED