Obligatory message: sign stealing is NOT against the rules. The kind of surveillance/scouting that Michigan was doing to get the signs is what was against the rules.
At one point during the Bronco era our defensive players openly bragged that we knew all of AFA's audibles. That's "sign stealing," but that's on AFA to change things up, not our players to pretend they don't know the audibles.
It was on Utah's opponents to change things up, not Utah to close their eyes and pretend they couldn't see the other team's signs.