While I would assume the same thing, he later said
"New York City will run properly. We’re gonna bring New York back. I love New York,” he said. “We’re going to do something for New York. I can’t tell you what yet, but we’re going to make New York great again"
so open to interpretation.
Kinda crazy for the federal government to step in because they don't like the outcome of an election
Now I think Mamdani is an idiot, but it's not Trump's place to step in