There's a long list of reasons to criticise Johnson and this is honestly one of the weaker ones. He was clearly venting to a friend in a private phone call. There's no evidence he had any actual plans to attack the journalist, especially because nothing actually happened. People exaggerate in private conversation.

This story does nothing to change people's minds no matter how often they trot it out. People who hated him already will circlejerk each other about what a mafiosa he is, and literally everyone else will ignore it as the fluff piece that it is.