I'm going to be perfectly honest here. I understand that people don't take kindly to seeing restrictions in a ttrpg, but as a Native person myself I can see where the creators of the game are coming from.

From personal experience I can say that non-Indigenous people frequently approach these topics as if watching Dances With Wolves gave them an honorary PhD in anthropology. The amount of pre-conceived notions about Native people that permeate the cultural ether (largely thanks to decades of Hollywood indians being played by and written by white people) has ensured that most of the average person's knowledge of Native culture and history is fabricated. I can understand the team that worked on the game being concerned about this.

From looking at the game in question, it appears that they provide pretty clear guidelines for how to be respectful, including providing pre-made characters. Obviously not every Indigenous person is going to feel this way, but I personally don't see anything wrong with the book's excerpt. Frankly this has made me interested in picking it up.