It is not about identity but the use of an identity to access money and power and publications.  It is a hot topic and why not pick an area where the money flows easily.  I think, and I am struggling here this is not about his ability as a writer, it is about trusting the narrator who has sold his work on the basis he is an authority on indigenous matters.  It would be an entirely different read if I were to buy it on the understanding he is a white man who is writing about the indigenous people.  Entirely different matter.