Bodybuilding isn't a sport since none of the workouts count towards any points or time winning records. It's not a game of any sort where competitors out score each other in the gym by the amount of sets they do or the weight they lift. The contests are the goal for amateurs and pros and then it's left up to a judge to decide whether or not they have a great physique. Beauty contests are the same way.
Now if they did one set of mandatory exercise (ie incline bench press) on stage then did a side chest pose right after hitting that set, then maybe it would be a sport.