The main problem with all of these scandals mounting up, as Trump has shown, is that if you only cause more and more scandals, none of them will loom that large, and people will quickly accept them as the new normal.
Johnson seems less able to double down on them. Trump would have been out in front of the argument story either denying it or making it into a joke. Controlling it for his base to lap up. Johnson just looks a bit worried and hoping for the best.
The main problem with all of these scandals mounting up, as Trump has shown, is that if you only cause more and more scandals, none of them will loom that large, and people will quickly accept them as the new normal.