I agree with Ms. Nagata's overall critique of cultural appropriation and the damaging effects it can have. While a product of cultural appropriation (a movie, a book, an inauthentic lūʻau performance) might be harmless in itself, for those whom they offend, they are felt to reenact and perpetuate the injustices of history. 

However, I depart from her view when she suggests that storytelling is necessarily a form of appropriation. Does one need to be Jewish to make a movie about the Holocaust? Does one need to be indigenous to make a film about indigenous people (I think the brilliant recent film, "Embrace of the Serpent" answers that question with a resounding no). The filmmakers have taken creative license with the source material, and some are likely find this offensive, but that does not mean a culture has been stolen or appropriated. 

Now, the money that Disney is going to make from the film is another matter, and one certainly worth the debate.