A controversial Q&A broadcast involving comments from Zaky Mallah didn’t cross the line in inciting Australians to join Islamic State terrorists, Peter Greste says.

The Australian journalist, who was released in February after spending 400 days in an Egyptian jail cell for reporting on political events following unrest, says the government is shooting the messenger in slamming the program.

The ABC, which admitted an error in judgment, has been heavily criticised for allowing the convicted criminal airtime during Monday night’s program.

Greste said the ABC could have handled the material more sensitively, but that the criticism that has followed is designed to shut down public discussion.

“Anything that closes down debate I think is a bad thing, as long as the debate doesn’t overstep the boundaries of becoming incitement ... and I don’t think that debate crossed that line,” Greste told a media lunch in Melbourne.

Peter Manning, a former executive producer of Four Corners and ex-head of ABC TV news and current affairs, told Crikey on Wednesday the ABC shouldn’t have apologised. “I think senior ABC management needs to get their act together to defend freedom of speech, and the Q&A program, and not buckle at the first whimper from the federal government as they did yesterday,” he said.

Greste also said the treatment of the Human Rights Commission president, Gillian Triggs, was another example of a public institution attacked to deflect attention from an issue critical of government.

“I think the way that the government has responded to it ... is deeply concerning,” he said. “What we’re seeing, I think, is an attack on the messenger increasingly, rather than engagement with the message.”

Australian Associated Press contributed to this report

