The biggest difference in a current strategic protectorate, Taiwan, and Greenland is that Taiwan saw the China threat and didn’t feel safe. Greenland doesn’t yet see the threat and does feel safe. Greenland is tied to Denmark, Denmark is in NATO, the US will protect NATO because no one else in NATO can. That’s the reasoning.
So has it occurred to you that the guarantee of the US defending NATO being less ironclad may be a good thing?
The US has slowly been moving to more of a directed protectorate model anyway. Taiwan, South Korea, Japan, Israel, Saudi Arabia, and several Pacific islands fall into this. The US provides them with security, with the understanding that they don’t upset the US too badly. They don’t sell things without the US okaying it, they don’t form alliances without US consent, several of them are obligated to pay much of the cost for US basing on their turf. A sugar daddy relationship. Eastern Europe is essentially going in the same direction. Western Europe knows it’s been running around on the sugar daddy and then claiming to have a headache when he’s in town. It won’t last. Greenland needs to be made aware of that, for our benefit and theirs.