Proposition:
We give the liberals a planet, and let them make of it what they will. It is their only planet, and last planet that they'll ever have. Any liberals who come along can go and live there rather than live in a free, capitalist galaxy.
Since liberals espouse population control through abortion, minimal impact on the environment, and other wholesome ideas, they should have no problem restricting their needs to the resources of a single planet. In their care, the planet should prosper and they should not suffer from extreme changes in climate or major natural disasters. There should be almost no pollution, and everybody should be gainfully employed due to their enlightened economic policies. Naturally, weapons of any kind will be outlawed so there should be no crime.
And if anybody should grow tired of their life on that planet, they can petition for refugee status in the greater, capitalist galaxy wide republic.
Let the liberals stay here.. We should go....
I've given this some thought, too.
There are a lot of ways that might work out, depending on which flavor of liberals we're talking about.
A colony consisting of Birkenstock-wearing naturalists would, a century after the initial colonization, most likely either degenerate into savagery or be limited to small bands of hunter-gatherers. The hunter-gatherer scenario seems most probable, since that's what many of them seem to really want. For their sake, I hope that their chosen world has soil that can support cannibis. LOL
At the other extreme lies a colony founded by hard-line Marxists. That would quickly descend into chaos as the "proletariat" escaped into the countryside just to get out from under the boots of the commissars.
The limousine leftists? Shee-it, they've got it too good to ever want to leave Earth.
Another possibility is a world colonized by scholars and scientists, who seem to tack to the left by default. Might even turn out to be a nice place. The potential dark underbelly of such a world would be that SOMEONE would be needed to do the grunt-work, thus raising the long-term possibility of a caste-based society, with the scientific "priesthood" reigning over everyone else through genetic manipulation, selective breeding, propaganda, or any combination thereof. ("Brave New World", indeed)