I've been following Urbit for a while now (maybe 6-7 years?), and over that time, it has gotten clearer about its goals and motives, I believe because initially they wanted to speak to a very small group of weirdos who saw what was on it and were intrigued to learn more. Starting from a small clique of like-minded people.
Now it's possible to understand what the idea is (some sort of VM running an esoteric set of languages to build an operating system that, among other things serves as a 'digital identity' of sorts). This is the point in time when they want people such as HN readers to understand it, so they make it so it can be understood (more or less). I also think the esotericism of the programming languages is also to prevent anyone from having a go, and to limit people who can program in these languages to just those who are heavily invested in them.
But as others have pointed out (including the author of the post), the idea is deeply terrible, and implements a sort of feudal network with kings, lords and peasants (galaxies, stars, planets), because Yarvin is a neo-reactionary who believes life was better when we had monarchies in charge of everything.
He does this at the same time as wanting a clean-slate programming environment, because computers these days are very complicated and buggy or something.
All of this speaks to a desire for things to be simple. Simple politics, simple computers. Democracy and computing these days are not simple, but that's because _humans_ are not simple, and if you want humans to have an equal voice and standing, then that's probably going to result in not-simple systems, in politics as in computing.
We should resist it, for the same reason we should resist anyone trying to agitate for feudal revolution.