After all it was just a few months ago that Key was confirming he regularly called Slater "to see what he's got on his site and mind".
He could just as easily have explained this week that one of the hallmarks of New Zealand is that we are a free society and while he wasn't going to go into all the detail of his private calls, he did often touch base with media - including Slater.
This may have inevitably led into a "dirty politics" cul de sac.
But surely there comes a point where Key should just simply stand up to Opposition attempts to cement Nicky Hager's book as the only political narrative of his Government?
He could also have quickly cleared the air by saying his Government was reassessing its communication strategies - it would be open with news media, not suppress material that should be released under the Official Information Act and was prepared to engage in debate on substantive issues.
Instead the Prime Minister's dismissive approach has simply resulted in him being the subject of criticism.
Hubris is a close companion to third term Governments and their leaders.
This is a tendency that Key will also need to guard against as his Government weighs the exact terms of New Zealand's forthcoming "military" engagement against extremists of Isis (Islamic State). It is important that Key prepares New Zealanders for the likely role that the country will play alongside other nations combating Isis.
So far, it's been a slow striptease as the Prime Minister softens New Zealanders for the involvement. Before the election, Key cited the upcoming electoral poll as a reason to duck the question until after the September 20 election. He's since said the Government is considering sending troops - "it's not a matter of if, but when".
The fundamental issue is whether Key will be direct with New Zealand about exactly why we are going into Iraq: What are the exact terms of the engagement? Is the SAS to be an active part of the military fighting forces against Isis? Or will it play a mentoring role alongside Iraqi forces? Or is the "mentoring role" simply obfuscation for the real combat role the SAS will play.
Labour has rightly said the rationale for the involvement must be stated along with the exit strategy.
There have also been suggestions that New Zealand's own "low" terror threat level could be lifted as the upshot of the siege in Canada's Parliament. This is premature. Key will be weighing any perceived intensification of risk to New Zealand as a result of the Canadian killing.
Media "talking points" sent accidentally to Newstalk ZB were telling. Foreign Affairs had advised him to call the shooting a "terrible act of violence". While there was expected to be debate on whether the shooting was in a retaliatory move as a result of Canada's role in the anti-Isis fight, "it's important to let the facts emerge from this incident".
Let's just flip this advice on its head. The facts that will justify the upcoming engagement are important and need to go much deeper than mere "talking points".