"Buffalo" or "bison," they are talking about the same thing. Where "bison" is the technical term for the beast (all true buffalo being restricted to Africa and Asia, I believe), "buffalo" is too ingrained in North American culture for many people to even know there is a difference.
I'm not sure whether to take it seriously or not. On the Sioux issue, it's naming a team after a group of people, which is just weird. On the Bison issue, it's not like once one group has claimed their (non-human) totem, no other group can.