The tables turned in David Seymour and Judith Collins' free speech debacle, with the former mocking the National MP for labelling a Green MP "just a kid".

Seymour and Collins were interviewed together by Magic Talk's Sean Plunket on Monday following the ACT leader's comment last week that Golriz Ghahraman was a "menace to freedom" in New Zealand.

Collins, 60, defended Ghahraman on Twitter, telling Seymour: "Please don't refer to Golriz in this way. I do not agree with almost anything she says, but she is a person and it does not assist political debate to dehumanise her like that."

She doubled down on her defence of Ghahraman on Monday, telling Magic Talk the Green MP, 38, was often been treated unfairly in Parliament and that she's "just a kid in my view, she's in her 30s" and "she's a young person".

Seymour, 35, then mocked the National MP, accusing her of committing a "searing ageist attack on Golriz", adding that he felt a "need to stand up for Golriz Ghahraman who, like me, is also in her 30s. That's a disgrace".

Ghahraman is the same age as Prime Minister Jacinda Ardern. She's not the first Green MP to have her age highlighted by another politician.

Paula Bennett, 50, criticised the Government for not taking cannabis legalisation seriously by "throwing something this important out to a very junior Member of Parliament", referring to 24-year-old Chlöe Swarbrick.