"We wouldn't attack people who weren't threatening to do any damage to New Zealand and it hadn't come to that point with Shane Jones.
"But now he is potentially a threat to the prosperity and stability of the country, I think it should be out there."
Jones said Seymour's attack was not worth commenting on. But asked if he considered himself to be such a threat to the country, he laughed at length and added "rest assured I'm not a political form of myrtle rust".
The year's bill was less than half the $253,000 former Foreign Minister Murray McCully spent in three months at the start of the year and Seymour admitted he did not know how it compared to other diplomats' costs or how effective Jones' work with MFAT had been.
"The reality is that the National Party put him there as a chess move to get him out of Labour because he was one of the more effective people Labour had. That isn't a very competitive field, but nevertheless."
However, he did not write off Jones' chances of winning in Whangarei, the city Seymour was raised in. He said it was hard to say how Jones would go against National's Shane Reti.
"It's hard to say because I don't know how (National MP) Shane Reti is going down. But one thing I know about Whangarei is people don't like wise guys and show boaters. He might find he gets a cooler reception than he thinks."
When it is pointed out former Act leader John Banks was Whangarei MP for many years in the National Party, Seymour said "yep, and look how that ended".
Seymour has been using the possibility of NZ First holding the balance of power to try to push his own campaign to prevent that happening. He said NZ First had been a disaster in the past. "So there is a serious point at stake here."
In Jones' four years at MFAT, he served as the economic ambassador for the Pacific, focusing on regional issues such as fisheries. Although based in New Zealand, he was also High Commissioner to Nauru, Mauritius and the Seychelles.
Unless he becomes a minister after the election, Jones also has a pay drop to look forward to. The OIA showed his MFAT salary was between $190,000 to $257,000. A backbench MP gets $160,000.