I would add what I wrote as well. Because using characters as a mouthpiece is something that happens. Being specific is best. I think if you added:here is what I will include in the rules:
There is to be no reference or allusion to current world politics. This is a made-up world. Let’s concentrate on the big ideas.
There is to be no reference or allusion to current world politics nor any using characters as a mouthpiece to espouse political views. This is a made-up world, etc.