So either:
Johnson didn't know what was happening in his own residence/place of work. Despite actually having been present at some of these events. Meaning he's incredibly thick, naive or gullible and not remotely fit to continue as PM
Or
he did notice these events, but was lied to by his senior staff about whether they broke the rules. Meaning he didn't know the rules he was ultimately responsible for setting in the first place or was too thick to understand them. And can't even command the loyalty of his closest aides who must be running rings around him. In which case he's not remotely fit to continue as PM
Or
(And this is obviously the right answer) He's been lying all along. And is not remotely fit to continue as PM.
Obviously JRM knows this. It's all one big joke to him. He is literally laughing at the people who voted for him, they all are.
And sticking a metaphorical two fingers up at the rest of us knowing full well there's **** all we can do about it.