> In space exploration, such barriers to movement don't exist

It takes a lot of training to operate a space station. Look at airplanes, which are less complicated. Pilots need training for a class of planes, and often for a single type. Switching between even different Airbus planes requires re-training - switching from Airbus to Boeing requires much more.

Upgrading a submarine can require "fundamental retraining for nearly 60 percent of the crew." http://www.public.navy.mil/subfor/underseawarfaremagazine/is...

Even for normal ground-based job, we often expect it will take a few months for a new employee to get up to speed.

Why should I believe there would be no re-training cost to switch between space station types? That re-training is a high barrier to movement.

> Then all the other space station dictators will get together, agree on some sort of "big charter" guaranteeing people rights,

So, a "United Nations" for space, backed by the point of a gun. And this will be more effective than the current UN how? And this would be different from current democracies, which "are always backed up with a police state that coerces you, at the point of a gun" ... how?

> What I'm getting at here is that the best political system for space exploration looks a lot like feudalism, though one full of yeomen (who were free to move about) rather than serfs (tied to the land). It's the only morally defensible system of government -- nobody is coerced to follow laws they dislike, but is able to vote with their feet, and choose the laws that best suite them.

"Feudalism" is an ill-defined term. See https://en.wikipedia.org/wiki/Feudalism#Challenges_to_the_fe... . I do not think it's wise to depend on Marx's 19th century feudalism model given the 150 years of development of archeology and history. I see the above proposal as being much closer to the Goðorð system in Iceland, based on traditional northern Germanic laws.