I don't know about the "fairness" claim. After all, we have his very damning Cornerstone speech, unabashed belief in white supremacy and slavery as the basis for the CSA.
Unfortunately there's not much on what his views were on Indians, at least that I know of. He was part of a Whig faction called the Young Indians. At the time it was common practice for those with romanticized views of Indians to publicly claim they were trying to take on their perceived qualities. (Think Tammany Hall, pre corruption days, named after Chief Tammanend. Or just think of the Boston Tea Party.) The YI faction was proclaiming their admiration of Indian tribes as fierce advocates of democracy.
OTH it's also common for those same people to argue Indians were "doomed" to die out, or needed to be saved or assimilated. Based on the admittedly very slim evidence, Stephens may be an advocate for cultural assimilation not much different than Richard Pratt.
http://historymatters.gmu.edu/d/4929/
An important note: There's far more than two Indian tribes in OK.