It was not intended as a universal admonition to Australians - he was talking specifically about the implications of the recent university massacre in Kenya - but coming from Greste it might as well have been a broader warning to be careful what you vote for.

When you've spent 400 days locked in an Egyptian prison for the crime of doing your job, you come decorated with a certain assumed moral authority. A tougher task is to wear that garb well. Peter Greste - as gently spoken as he is persuasive of view - carried the garlands effortlessly. He commanded the field so easily that once again you wondered why Q&A had not dispensed with its five-panel tradition and handed the floor to its star attraction.

He showed that when one's recent life experiences put one's beliefs to the test, gratitude only goes so far. Greste has recently been effusive in his thanks for the efforts made towards his release by politicians - notably and correctly, to Foreign Minister Julie Bishop, whose face-to-face diplomacy on his behalf he compared a few weeks back to her counterparts being "hugged by the Terminator".

Of course, Greste's fight for freedom was a bipartisan issue - as bipartisan, for example, as the debate over data retention. Or, for another example, the fight against terrorism being summoned as justification for almost anything. Or, for yet another bipartisan embrace of a focus group winner, the dog-whistle demonisation of a particular religious group.

Whatever their support for him personally, Greste was not about to give either major party a free pass on these shortcomings, even if he didn't make reference to either in his answers. The implication of his experience brought the weight.

He was at his most powerful in response to an audience question on the Koran and its alleged influence on terrorist acts.

His opening line dispatched the obvious but necessary: "I think if you dig around the Bible you'll find plenty of excuses as well."

Then he went on.

"Look, there are 1.5 billion Muslims in the world today, 23 per cent of the world's population is Islamic. We're not at war with 23 per cent of the world's population," he said.

"We can dig around and find all sorts of excuses. To my mind this is one of the biggest problems. This is not a clash of civilisations."

Greste argued eloquently against the recently legislated collection of metadata - "we're creating a lot of dark spaces within government" -  and warned against falling into line a behind policy built around what host Tony Jones called "the T word".

Did Greste think Australia was exempt from politicians invoking it to justify their agenda?

"No, I don't," Greste replied.

"I think terrorism is clearly a big issue  ... but I think there is a real danger that terrorism is used as a kind of scare tactic, as this way of government taking it as an opportunity to impose all sorts of draconian restrictions and limitations which it would never get away with under other circumstances."

Greste's presence had his two fellow panellists from the federal parliament - the Coalition's Mitch Fifield and Labor's Alannah MacTiernan - scrabbling to find areas of agreement with their heroic Q&A desk partner.

Fifield tried this, on the question of a global code of governance for the rights of journalists: "We've got to acknowledge that Peter has earned the right through his unique commitment to freedom of the press to have any proposition that he puts forward seriously looked at."

But Fifield, like MacTiernan, was pushing the proverbial uphill, as when the Labor MP tried to have it both ways on Labor's support for the metadata bill. As Jones told her: "That sort of begs the question as to why you voted for it."

Indeed it did, and it was a question she couldn't properly answer. It made you wonder, how would your run-of-the-mill Aussie pollie answer other questions, such as this one to Greste: just how did he get through those 400 days?

If you'd told him what awaited beforehand, "I'd have thought I'd go mad", he admitted. But when asked to answer the challenge, he'd learned: "I'm tougher than I thought I was."

And that summed it up: in Greste's presence, the politicians were left to wonder what a really tough question looks like.