Native here - Canadian Ojibway/Cree in case you guys are curious
First off, I'm not a Native fascist, anarchist or fundamentalist - I think I am a lot like a lot of people and have a weird fascination with 1930s Germany and the crazy shit they did back then - I saw your thread and thought to myself ... what if there ever happened to be a Nazi Indian.
Their flag would probably look more like this. Simple, to the point and with no symbolism that tied to any other cultural group or tradition except for their own.
Think about it. The promoters of this flag and its symbol want it to be easy to identify and easy to reproduce - like what the Nazis did in Germany. In addition, this simple image of the Thunderbird, a powerful symbolic animal spirit in Native culture is easy to reproduce. All a Native supporter would need is some black charcoal and they could draw this out on a building, a roadway, a field or on the side of a burned out army tank.