Whatever happened to that libertarian philosophy of letting the people living there decide what to do with it?
That's not libertarian philosophy at all. It's socialist or third way (not left or right), but it's certainly not capitalist, free-market democracy.
In a capitalist, free-market system, money rules. Libertarians are activists for the rights of corporations and offshore bank accounts.
Those with the most money and power have issued so much money to themselves and their cabal that they RAN OUT of places to own. The only places they don't own are the few remaining independent states (made into enemies of the USA), or restricted areas, like Antarctica and tiny segments of unsettled areas, protected areas. You know, Western Sahara was one, they scored it recently. Greenland, although technically still part of the Danish Crown (remnant of Christian monarchist age), was granted indigenous rule, for its own matters, by the Crown. Still, it's the crown's decision on what to do wth Greenland.
For centuries, non-Christian capital and communism waged revolution and regime change against the Catholic and Protestant kingdoms. Sometimes by force, sometimes by growth of power and influence. We're in the late stage now. So, if you're a lib, ("classical liberal"), you don't stand for "man on the land" rights, you don't give two hoots about some scrotty tribes and their folk tales. Unless they are one of you. A rare exception. So, be consistent. Be a libertarian and let them buy Greenland or force their way in militarily or otherwise with the mammon power and the boss mode. Fountainhead.