Perhaps not as flammable as the fightin' n<censored>skins, but I think it has a history of derogatory usage beyond a simple comparable of color of skin. Yellow man, maybe, but I think closer to chink. The redskin usage is uncommon enough today that it doesn't seem at all to rise to the level of the n-word*, but I think its history is more bleak than recently memory has it. Having not done any reading on it beyond this topic, probably makes me unqualified to judge a comparison between the two.
If they approached the tribes, I wonder if any of them would take them up on some kind of offer. The Seminoles were mentioned earlier, but redskin is general enough I am not sure any tribe would want to touch it.
* At some point I will be adult enough to simply type n-word out correctly like I did chink, but something always holds me back. I think I fear Richard Pryor (or maybe Michael Richards) yelling at me from the stage.