Otago University politics lecturer Bryce Edwards said the decision signalled a warning to media.
"You have to be careful, you have to not challenge the powers that be, not take too strong a role in keeping the Government of the day and other politicians held to account," he said. "That's just incredibly dangerous. This is the kind of thing we expect in more authoritarian countries than New Zealand."
Dr Edwards noted other freelance journalists had been singled out by the Government, including Jon Stephenson and Nicky Hager, who came under fire this year for their reporting on New Zealand's involvement in Afghanistan.
Mainstream media outlets had also been subjected to the Government's "extraordinarily aggressive and hostile" approach, he said.
He cited Speaker Lockwood Smith's banning of the New Zealand Herald from the parliamentary press gallery for 10 days after a reporter photographed a protester in the public gallery in the House.
"That was quite a strong reaction which just suggests that at the moment, the Government is very sensitive about the media, and they are flexing their muscles and making sure that any journalists or members of the media who push the boundaries are heavily dealt with."
Dr Edwards said it was legitimately in the public interest for Ambrose to seek a High Court ruling on the tapes.
The decision to seek costs was "petty" and could have a chilling effect, he said.
"It's an area that politicians and the state should keep out of as much as possible."
It was "extraordinary" that the independent Solicitor-General, who was responsible for whether or not to seek costs, would make such a decision.
"It either questions their independence or their judgment," Dr Edwards said. "Because it's dealing with such a heavily politicised issue that was at the centre of the recent general election, it either suggests that the Solicitor-General is making decisions that are really doing the bidding of the Government of the day, or they're being incredibly naive."
