Lordy did that one hit me good. Couple days ago I had a woman go absolutely ballistic on me because she overheard a conversation I was having with someone else. I responded to a statement with, (paraphrasing here) 'Commanche used to go full ISIS on their neighbors. Ask any Apache or Texas Ranger, they'll tell ya.'
I agree with your last sentence too, with the qualifier of that area seems to have a lot of people who are particularly hostile to information that might cause a worldview re-evaluation.
The more positive modern view of natives is meant to counteract a long history of severe discrimination.
The "did you know blacks profited from the slave trade" people are hardly the historians among us.