What you're missing is that this is something that will happen anyway, explicit CoC or not. Someone with power will always be in a position to judge the rules and enforce them in his own way on someone without power, by definition.

But if there is an explicit code, you are warned in advance of the actions that will more likely trigger enforcement, instead of finding them after the fact.

Therefore, you can decide to avoid those actions, or avoid the event entirely. In some ways, an explicit CoC is giving more power to participants over the organizer, not the opposite.