When Scott Morrison promised to abolish the right of religious schools to expel gay students because of their sexual orientation, his motive was obvious – and so was what would inevitably happen next.

Morrison insults people’s intelligence by claiming his move is unrelated to the Wentworth byelection. You don’t say you must deal immediately with a single matter from a report that you won’t yet release unless there is some political imperative.

Wentworth has a large gay population, and a leak from the Ruddock report on religious freedom gave independent Kerryn Phelps – the Liberals’ main opponent – an issue to exploit. So Morrison played the fixer.

But it was clear that once he addressed the question of students, the debate would focus on teachers. That’s much more difficult for a Liberal prime minister, very religious himself, who has a strong right wing in his party.

Read more: Coalition trails 47-53% in Newspoll, as Ipsos finds 74% oppose law discriminating against gay students and teachers

The existing law (and the tweaked one that was proposed by the Ruddock inquiry) allows these schools to discriminate against both students and teachers. While the situation of the students might appear more outrageous, in practical terms the coverage of teachers affects more people.

This was ripe for a counter-move by Bill Shorten. On Monday the opposition leader called for a wider change.

“I’m pleased both sides of politics are now united in the view that exemptions allowing religious schools to discriminate against children should be removed”, Shorten said.

“I believe we can use this goodwill to go further and remove the exemption that would allow a teacher or school staff member to be sacked or refused employment because of their sexual orientation.

These laws are no longer appropriate, if indeed they ever were appropriate.” (The current law dates from Labor’s time.)

Predictably this was a step too far for the government, even under the pressure of Wentworth.

Read more: Politics podcast: The battle for Wentworth

Morrison argued in parliament that while students needed to be protected “urgently”, there would be “a time and a place to address” other issues from the Ruddock review.

Advocating a ban on discrimination against teachers would take Morrison onto very sticky ground among conservatives in his ranks and some figures in the churches. (It will be interesting to see whether Labor comes under some church pressure for its stand.)

The Anglican Archbishop of Sydney, Glenn Davies, while supporting Morrison’s position on students, said church schools “should not be forced to play by secular rules. … Anglican schools, if they are going to remain Anglican, must be able to employ staff who support the Christian values of the school”.

Despite Morrison wanting to push the teacher issue off, deputy Liberal leader Josh Frydenberg was willing to put a stake in the ground. “I don’t think there’s any room for discrimination … be it a student or against a teacher,” he told the ABC, while adding, “that being said, we need to work through this process with the Labor Party and ensure that we can provide a bipartisan front to the country.”

Campaigning in Wentworth, Liberal candidate Dave Sharma, appearing at a candidates’ forum, denounced discrimination against teachers, and said the 2013 law should be changed.

As the Liberals fight for survival in the seat – which is also a fight for the survival of the government’s parliamentary majority - Sharma now seems to be going for broke, telling the locals he had been “appalled” at how Malcolm Turnbull had been treated. This is not a candidate going rogue - he has been let off the leash to maximise his chances.

But Sharma won’t be helped in this progressive electorate by the government’s extraordinary decision to support Pauline Hanson’s (unsuccessful) motion on Monday calling on the Senate to acknowledge “the deplorable rise of anti-white racism and attacks on Western civilisation” and that “it is OK to be white.” This will take some explaining in Wentworth.

The amendment on students is not expected to go to Tuesday’s Coalition party meeting. Maybe drafting is taking a while, or perhaps the government, now it has announced its plan, would prefer to leave the detailed discussion until next week, after Wentworth.

Even the precise terms of the amendment are uncertain. The government refers to expulsion, but what about enrolments, which are covered by the present wide provision?

When asked by The Conversation to clarify, a spokesman for Attorney-General Christian Porter said: “Our amendments will be broad enough to minimise the risk of students at independent schools facing discrimination, while at the same time respecting the right of religious schools to run their schools in line with their beliefs and traditions.”

Some sources say the amendment will be confined to expulsion.

The opposition and others will keep the teacher issue running to get maximum exposure before Saturday. Senate motions are planned. The Labor one calls for immediate legislation to “abolish the current exemptions that permit discrimination against LGBTI students and staff in religious schools”, and also for the government to release the Ruddock report at once.

Some Liberals who agitated for action on religious freedom might be starting to appreciate that the best stand for a conservative can sometimes be just to leave things alone.

The Ruddock review was a concession to those opposed to same-sex marriage.

But the fallout from it so far has been pressure to roll back privileges accorded to religions, rather than to extend them – quite the opposite to the direction in which Morrison appeared to be heading only weeks ago.