There is a chance that letting someone so retarded run, would help the reasonable candidate. You are right, though. This is the country that elected Bush twice. There could be more problems at the polls. Moving to a mountain in the Yukon, if he gets a landslide. There is no saving the world after that.
I think it is naive to say that either Bush or Trump are unintelligent. I'm not a fan of either but they get things done. Unfortunately, Bush got things done that I didn't agree with and I'm pretty sure Trump would follow suit (see what I did there). In order to be so effective at getting your agenda pushed though, you can't be "stupid." At least IMO. If you are a democrat, I think to refer to Trump as unintelligent would be dangerous. He's a real threat.