Well, the way that it phrased is says "use of artificial aids". If you're just wearing spurs in a showmanship class, you're not using them in the class. There is no way to make use of spurs in an in-hand class. With that said, it is up to the judge to interpret the rule book and make a call, so you could be DQed or not based on the judge's interpretation.
My sister was disqualified from a driving class for wearing a pair of English spurs in the class. She had been in a riding class and forgot to take them off before hitching up for her pleasure driving class. Though there were no specifics in the rule book about having spurs on your boots, the judge deemed them a safety hazard and dismissed her from the class. A showmanship judge could easily do the same, no matter what is spelled out in the rule book.