There is a huge difference between having a mascot that is the actual name of a tribe (Utes, Seminoles,etc) than having a name like Indians, Redskins, even Braves or Warriors (depending on the logo and mascot used). If a sovereign tribe like the Ute have given their blessing, I’m not sure that the PAC 12 would want to wade into that PR nightmare (of course, given how badly the PAC 12 is run, who knows). The NCAA tries this about a decade ago and it failed in the cases of actual tribal names.