He didn't have to list him #5 because he may have known already that Jokic was never going to win a 3rd straight, so why list him?
List a different player who made an impact for their team

Mark Jackson probably felt the same way I'm feeling, let somebody else who's great get some acknowledgement. Jokic got enough of that already.
He left him off because since the beginning of the season it was pretty much established that Jokic wasn't winning another one in a row. Giannis would've had a better shot at winning his 3rd rather than Jokic for numerous reasons, one being that he hasn't won MVP in a 2-3 years so awarding him his 3rd would've been more easier to digest.
Jokic won't win another one for a few years.
The same thing happened with Bron in 2011 when Rose won MVP, he could've had his 3rd straight but they had to break up the monotony.