Does anyone believe Trump would campaign for Desantis if Desantis was the nominee? I don’t. Trump doesn’t need others to campaign for him anyway. Wouldn’t be very helpful. You either support Trump or you don’t.
And DeSantis risks looking like he doesn't. If DeSantis campaigns for Trump, it helps DeSantis more than it helps Trump. DeSantis should think of the future more than today or tomorrow.
Trump did endorse DeSantis for both of his gubernatorial runs.