He trumped out that hoary old chestnut that the media was heavily biased against Labour and that somehow journalists managed to skew the news so effectively that everything Labour politicians said was misrepresented or rubbished whereas National survived under a cloak of media protection.
To his credit Sainsbury didn't do what I would surely have been tempted to do in his position, that is tell the poor man to progress to the present day and get real.
Instead the radio host treated him a little gently and then demolished him by asking the caller to name a single instance when that had happened.
He was, of course, unable to.
We journalists can be accused of many things, cynicism being among them, but in nearly 40 years in the job I can't recall a single instance of a political party being favoured above another.
I can recall many occasions when politicians of all colours and creeds have made goats of themselves by something they have said or done and have suffered media exposure as a result.