That poll was later found to be not even remotely statistically valid. Later polls done by Quinnipiac and other schools of Native Americans put the numbers between around 65% to 70% opposed, with one outlier poll at, IIRC, 54% opposed.
I know a number of Native Americans and every single one of them is strongly opposed to the name. A number of years ago I was at a writer's conference in KC, held at a large hotel. Also held at the hotel was a conference of Native Americans on, IIRC, providing medical services to Native Americans. One evening, in a fantastic collision of the stereotypes of drunken writers and drunken Native Americans, me and two other writers were talking to five Native Americans in one of the hotel's bars. This subject came up. The Native Americans weren't overly concerned about most of the team names. They even felt that changing ND States name from the Fighting Sioux was unnecessary. But they were all strongly opposed to Redskins. As one put it "What would you think if they were called the Washington Jungle Bunnies? Redskins means the same thing to us."