Phil Goff should take note, this is how a leader should deal with idiots in their ranks. Own up. Norman denies any involvement of the Greens in the defacing of Nationals billboards. He then finds out that one of them did. Rather than waiting for someone to find out he punishes the idiot that did it and then owns up, showing the electorate that he has dealt with it.
I don't by the way, disagree with the sentiments expressed by the additions to Nationals billboards. If it was a random member of the public, it's still probably illegal, but most people will wave it off. If you are in anyway connected with on opposition party, especially a smaller one trying to establish itself, you'd have to be a sodding idiot to be involved. When caught it potentially damages the cause they're trying to further. I hereby find Russell Normans actions acceptable.