He's still president-elect. He can't do any work as president until January.
Maybe this is Trump's attempt to stay in the public eye to help lower his chances of being assassinated until he gets sworn in?
Trump is going to basically perpetually campaign to try and keep his stock up if he's going for a second term.
And nobody can really counter it because it's not officially campaigning and opponents won't be able to do anything like it until close to the elections.