The thing about David Brin is that, while he can write impressive worlds and plots (provided he limits himself to one volume), he simply can't manage to write the world from the perspective of anyone who is non-white, non-male, non-Western. This leads to most any character of his who is not a white, Western male being caricatured or hollow.

A Maori character contemplates the hierarchy of "ethnicity chic", the top standing in which belongs to the most tribal, the most primitive. The very concept of ethnic chic (as hooks et al have pointed out for years and years) can only exist from a white viewpoint. Only from an outside perspective, the viewpoint of someone who has sufficient privilege and cultural capital to not be affected by it, does this "hierarchy" have meaning or even existence. It's fetishization, plain and simple, placed in the mouth of a victim thereof.

It isn't that Brin doesn't try. He does. He just fails. He can't quite manage to write a depiction of another culture or gender or ethnicity that doesn't come out either cartoonish and overblown (eg "Dr. Pak's Preschool") or as a sort of mask over a character-shape that is, at core, white and male and Western (eg Fibbin, Athaclena, Teresa Tikhana).