The problem is that Rockstar doesn't aim for historical accuracy in terms of the characters. This isn't Assassin's Creed after all. In many ways I like the fact that Rockstar doesn't just throw random historical figures into their game however they could create characters loosely based on them. In my mind the best thing for RDR 3 is to go even further back in time with an eventual finale at the blackwater massacre as we still don't fully know what happened there but that's just my opinion.
