Gets people on both sides engaged and takes over the headlines and the hope is that it wipes partygate off the headlines and short term memory loss sets in and everyone forgets about partygate by election time.

Trump would just say something completely insane every other day to keep the headlines thrashing on nonsense to distract away from whatever else was going on.

Also think this is similar to the way that Klopp whines about the length of the grass after losses to keep media attention on what nonsense he's saying in pressers and off the performance of his players on the pitch.