They don't have to.
The NCAA is a private club, and therefore can set its own rules. UND doesn't have to belong; but if the University wants to be a part of the NCAA, the rules are clearly laid out.
Now, but an act of the state legislature, the University cannot comply with the club rules.
1st level worst case: the Sioux get into post-season play and wear generic uniforms.
2nd level worst case: who the heck knows?
I don't, however, see the NCAA kicking the University out of the club.