Nominating the elderly white guy would deprive Trump of his favorite weapon–identity politics. It would mean he couldn’t run against Hillary Clinton again. It also means that he won’t be able to sell a “socialism” argument to swing voters. So–other than talking about the big, bad Ukrainians, of course– how would he campaign against Biden?
By going back to an old argument in the GOP playbook. Remember, to a Republican, every GOP nominee is Ronald Reagan, and every Democrat is the weak, ineffectual Jimmy Carter. Trump will argue that Biden is just an extension of Obama, and that America from 2009 to 2016 looked like America in 1979; the economy was weak, crime was soaring, illegal immigrants were running wild, China and Iran remained unchecked, and America was disrespected throughout the world. According to the narrative, Trump and his swagger made America great again over the last four years. You wouldn’t want to put that at risk, would you?
This is so much hogwash, of course. Could he get enough swing voters to ignore their actual experience and buy into it? Maybe.