Offered 700 Billion or not - you make a good point.
The US has militarily protected Greenland since World War II.
We still have Pituffik Space Base (Thule Air Base) and there is no reason why additional peacekeeping forces could not be directed there.
You make a good point, too. Now just for fun: we really, really need Pituffik Space Base (also a NORAD base) for our Santa Tracker! (Yeah, I’m a sentimental softie who loves me some Santa Tracker.)