It's primarily an ego thing.
If Trump wins again now in a rematch and gets a 2nd non-consecutive term while their guy dies forever remembered as a 1 term loser (Let's be real: Biden's body, mind or both ain't making it to 2028), that's arguably more humiliating than if Trump had just won 2 times in a row, and they know it.
Yeah, I think it's this. They want a well-spoken guy in a suit calmly explaining things, they want the news to say this guy's policies are good, they want the occasional fiery speech but only in moderation and when the news says its for an important crisis. The policies don't matter in the slightest.