Peter Dutton has advised Alan Joyce and other business executives who have written to Malcolm Turnbull urging action on same-sex marriage to “stick to their knitting”. It’s advice some in the government would think he himself should take.

Dutton has launched a sustained jihad against the more than 30 business leaders who signed the letter, returning to the fray in his weekend speech to the Queensland Liberal National Party State Council and a press conference.

While he might argue this issue transcends portfolios, his strident intervention unhelpfully adds to Turnbull’s problem with freelancing ministers and highlights divisions within the government. In response, fellow cabinet ministers Julie Bishop and Simon Birmingham publicly defended the business leaders’ right to have their say.

Birmingham didn’t mince words. “I think throughout history, business leaders have often stepped ahead of legislators in supporting reforms related to gender equity or racial equity. And I see no reason as to why business leaders are not free to do likewise when it comes to issues like marriage equality.”

Dutton’s attack deserves close attention because he is seen, and sees himself, as the conservatives’ flag-waver in cabinet and has recently been talked up in the media as a possible future leader.

In their letter, the business leaders said “the time has come to resolve this important reform”, calling on Turnbull “to legislate for marriage equality so the government can get on with its core economic agenda”.

They outlined what they saw as a “compelling” business case for change. This included the interests of their employees, meeting the values of customers, and Australia’s global reputation as a welcoming and inclusive nation.

Dutton’s counter was scattergun. Speaking to 2GB’s Ray Hadley last week he ranged from denouncing the business leaders’ right to act as they did to his personal gripe with Telstra’s customer service.

Delivering “a shot across their bow”, he told Hadley that CEOs on big dollars should concentrate on their businesses and the improvement of the economy. Social issues should be left “up to the politicians, to the leaders, to talkback hosts like yourself, to normal people who can have those discussions without the millions of dollars being thrown behind campaigns because somehow it makes the board feel better or meets their social obligation”.

He had a serious dummy spit over his home phone. “My view of Telstra is that they’d be better off to concentrate their efforts on cleaning up their call centre operations because we had a problem with our phone at home last week … I lead a fairly busy life, the thought of hanging on the phone for an hour to some person in the Philippines and still getting nowhere at the end of the call drives me crazy.

"Now, here’s a suggestion for Telstra. Instead of getting caught up and spending you investors’ money, your shareholders’ money on all these political causes, what about tidying up your own backyard first and providing a proper standard of care and service to your customers?”

At the weekend it was the turn of Qantas to be singled out. “Alan Joyce, the individual, is perfectly entitled to campaign for, and spend his hard earned money on, any issue he sees fit, but don’t do it in the official capacity and with shareholders’ money. And certainly don’t use an iconic brand and the might of a multi-billion dollar business on issues best left to the judgement of individuals and elected decision-makers.”

And – in the wake of social media pressure forcing Coopers Brewery to back away from its association with a Bible Society ad featuring a same-sex marriage debate between two Liberal MPs – Dutton said it was “unconscionable” that some companies were “morally coerced into supporting campaigns in fear of being extorted by an online social media push to boycott their product”.

Dutton casts himself as championing freedom of speech. But in today’s acrimonious culture war, those calling for more free speech are squealing increasingly loudly when others exercise their freedom in a way they don’t like.

This indeed was the business leaders speaking freely, and they obviously believe their stand will advance or protect their businesses’ interests.

One wonders if Dutton would be lashing out if they had written to Turnbull supporting a change in Section 18C of the Racial Discrimination Act in the name of freedom of speech.

As for his argument that the CEOs are using shareholder funds, Dutton has so far produced no backup for this, unless he is referring to their own salaries.

When it comes to social media, the exhortations by online campaigns for people to boycott products surely falls under “freedom of speech”. (It’s a different matter if substantive threats are made.)

The tone of these campaigns can be offensive – but remember that in the 18C debate, the conservatives want the removal of the reference to “offend”.

Dutton has a particular interest in GetUp’s ability to campaign. GetUp mobilised against him at the last election, when his margin was cut.

Meanwhile Turnbull continues to stick to the plebiscite policy on same-sex marriage. He has little option.

Dutton was blunt at the weekend: “The party’s position has been very clear and we are not going to deviate from that position.”

For some of the conservatives, same-sex marriage has become rather like the carbon issue was in 2009, when Turnbull was opposition leader.

Then, many in his party were unhappy with him, as many are at present.

His commitment to an emissions trading scheme lit the fuse. Bizarre as it sounds, a fuse could be lit if Turnbull walked away from the plebiscite policy to embrace a parliamentary vote, as the business leaders want. Which is presumably why he won’t do it any time soon, although how he gets to a viable policy to take to the election is anyone’s guess.

Most immediately, he has to deal with the issue of Section 18C. This is due to go to cabinet for discussion on Monday. A report from a parliamentary inquiry recommended a suite of changes to the processes of the Human Rights Commission but left open the question of the future of the wording “to offend, insult, humiliate or intimidate” that the conservatives want changed.

The politically savvy course – especially with a view to campaigning in seats with large ethnic votes – would be to fix the processes and leave the wording. But that won’t satisfy those conservatives set on a culture war mission.

Postscript

As parliament resumes on Monday, Newspoll in The Australian sees an improvement in the Government’s position and that of Malcolm Turnbull.

Labor’s two-party lead has been cut to 52-48%, compared with 55-45% three weeks ago.

The Coalition’s primary vote has risen from 34% to 37%, while Labor’s has fallen from 37% to 35%. The Greens are down a point to 9%.

Turnbull leads Bill Shorten as better prime minister by 14 points (43-29%) compared with his seven-point lead in the last poll, at the end of February. Turnbull’s net satisfaction has improved from minus 30 to minus 27, while Shorten’s has worsened from minus 26 to minus 28.