Malcolm Turnbull says John Howard could assist the government in “fine-tuning” the exposure draft for any same-sex marriage legislation if the postal survey returns a yes vote.

Noting that the former prime minister had not made a submission to a parliamentary committee convened specifically to consider issues such as religious freedom after the legalisation of marriage equality, Turnbull said, nonetheless, he would welcome Howard’s experience and expertise, and his passion for detail.

“I am sure John will make an enormous contribution,” the prime minister told Sky News on Friday.

Turnbull’s response followed another public intervention by Howard in the marriage equality debate, when he accused the government of failing to deal with the matter of religious freedom before the postal survey went ahead.

Howard on Thursday released a sharp statement to the media warning if the yes vote triumphed in the postal survey there would be overwhelming pressure to legislate as quickly as possible, leaving scant opportunity to include proper religious protections in the legislation.

But Turnbull said the government would protect religious freedom and the question had already been considered thoroughly by a parliamentary committee last year.

He said the parliament could also amend any bill to legalise same-sex marriage during chamber debate in the event Australians voted yes.

“John Howard knows very well, because there were free votes that were conducted under his time as prime minister, private members will get a bill to protect religious freedoms and there could be an amendment here and an amendment there, a debate about this and a debate about that,” he said.

“No doubt it will be amended and debated and we don’t have a majority in the Senate and, in any event, it is a free vote.”

In an interview marking the two-year anniversary of his prime ministership, Turnbull also sideswiped his predecessor, Tony Abbott, who on Thursday suggested Australia did not have to meet its commitments in the Paris climate accord.

The prime minister said Abbott’s assertion that Paris was only aspirational was “not, in fact, the case”.

For his part, Abbott marked the two-year anniversary of his losing the prime ministership to Turnbull by giving an interview with the Daily Telegraph.

Abbott said during the interview that he would have won last year’s election against Bill Shorten if he had been leading the Liberal party.

“Absolutely. There’s absolutely no doubt,” Abbott reportedly said. “I’m not going to speculate or make comparisons but I have not the slightest doubt that the government would have won last year’s election under my leadership. Not the slightest doubt.

“Obviously 14 September 2015 wasn’t a great day in my life but the last thing I am going to do is let one bad day ruin six good years. They were good years.

“It still hurts … but most people at some point in their life have disappointments and you’ve just got to put it behind you and make the most of every day and that’s what I’m doing.”