I didn't read this as him trolling Trump, I read this as him trolling Biden.
He is bringing to everybody's attention that half of the country doesn't accept Biden as the legitimate winner of the election. Even in the context of a ribbing/joke, it still reinforces a reality that the Biden Administration would likely be kept out of the spotlight.
Imagine if a Chinese citizen made this same joke about President Xi, in a similar context. How long do you think that individual would remain alive?