Most people really don't know enough about the actual tribes that lived on their land. A good example of that would be the fact that most Native Americans were nomadic hunter gatherers who either followed bison migration or were semi sedentary farmers. Most tribes were not a hegemony, and the concept of an Indian "nation" was a product of 19th century politics. Then try explaining the Chippewa-Sioux wars in Minnesota or Tonkawa Scouts cannibalizing Comanches in the American Southwest to someone whose understanding of Indians is "oppressed brown people". That's the mindset they have, at least the ones who actually believe in it, I don't think the organizers believe it at all.