Yes he does think that, because at that point, the alternative is to vote for Biden. He expects former Trump will support the GOP nominee, because the alternative is four more years of Biden .
He can think whatever he wants to think, but he’s grossly underestimating MAGA loyalty. If DeSantis thinks that he can trash the man who first activated and engaged them yet still generate enthusiasm he’ll have another thing coming. Do you think Donald Trump will show up at a DeSantis-nominating convention or make commercials for him? I don’t. DeSantis is building a reservoir of ill will by taking cheap shots.