The suit stuff aside, what’s with his weird grammar? “You have not done a good job by the people in Greenland.” In this sort of sentence, “for” sounds much more natural than “by”. And I think the common phrase that “Person A hasn’t done right by Person B,” is more of an exception.

But assuming he did mean it that way, then he’s speaking as if the people of Greenland feel wronged by Denmark, but they don’t.

In fact, Americans are much more disappointed with Trump and Vance than Greenlanders are disappointed with Denmark. If disapproval rating was the important thing, then Denmark would be acquiring the United States.