Trump literally got into a heated exchange with the Danish representative. https://www.yahoo.com/news/trump-had-horrendous-call-danish-193412504.html He is quite serious, because he's all into the sort of government that could shift into the Project 2025 dictatorship he wants, and that's imperialism. He's setting up the ground for the fake outrage that will fuel actions that would otherwise be indefensible. They will still be indefensible, but doing it overtime allows him to prune his critics from any position of influence.
The consolidation of his power is probably true, but even in that context I'd say demonizing Denmark is probably a swing and a miss. I still say there's no plausible chain of events where this ends with Greenland as part of the United States.
There's a very possible line of events leading to the expansion of already present US bases in Greenland expanding and coordinating with private interests to exploit its natural resources. The US doesn't want Greenland, they want their resources. He would be quite capable of stopping financial aid to Greenland related to those bases while refusing to move troops out to egg a response, and then using that response to justify even more forceful measures.