That's a lot of bullshit. While the specific words might be more or less problematic, the big problem is that it objectifies people. Devils, Bulls, Tigers, Lions . . . Indians.
By contrast, there are no teams nicknamed "whiteys" or anything of the sort (save possibly Celtics, whose origins I don't know). The names that apply to people are named after professions or roles, so to speak (e.g. Pirates, Deacons, Cavaliers) or have geographic relevance (as we all well know). But teams weren't named Indians or Redskins because they were local markers. They were named Indians because Indians sounded tough and scary. The whole idea is racist.
I don't know why the Seminole tribe has embraced its use. I'm sure they have good reasons. I don't know them, not really. But for the most part, native Americans do not like being sports mascots -- just like other Americans (hence the lack of "redneck" teams).
Redskins in particular would be like having a team named the slants with an Asian mascot.