During the election he showed up at the scene of a flood, wielded a mop for the cameras- and people thought he was taking the piss. To stop this happening again he has decided to stay away from the latest floods- and people think he doesn't care.
Damned if he does, damned if he doesn't.
It's his own fault, of course: By pratting about to win votes he undermined his future authority.
A younger man might have been able to pull a Prince Hal and impress the nation with his new-found righteousness and resolution, but Johnson is already long in years...