There’s a couple of perfectly good replacements for Cory Bernardi in the role of Shadow Parliamentary Secretary for Disabilities, Carers and the Voluntary Sector.

One is Sue Boyce, the Queensland senator and former journalist and businesswoman who has worked tirelessly on disability and carers’ issues for years. She used to be President of the Down Syndrome Association of Queensland and knows the area inside out, although no one will have forgotten her missing a crucial Senate vote last year. Yesterday, while Bernardi was declining to say sorry and shake hands over his playground spat with Christopher Pyne, Boyce was calling for consideration of the proposal by the Director-General of the NSW Department of Ageing, Disability and Home Care, Brendan O’Reilly, that the Medicare surcharge be increased to provide for the care of people with lifelong disabilities.

Currently, there is no consistency at all in terms of Government assistance for people with severe disabilities, and those born with a disability face a much grimmer financial future than those who incur a disability through work or a motor vehicle accident. There are some Coalition MPs who are still doing their jobs.

The other is young South Australian senator Simon Birmingham. Birmingham has no experience in the area, but is one of the smartest Liberal backbenchers and is a future star of the party. He was overlooked when Malcolm Turnbull replaced Fiona Nash with Mark Coulton as shadow Parliamentary Secretary for Water Resources, despite Birmingham being one of the best Coalition analysts of Murray-Darling Basin issues.

Two excellent candidates — one with considerable expertise and contacts in the sector, the other a promising young talent.

Both, however, are moderates. Birmingham is a former staffer to Robert Hill. One Liberal MP said “his promotion would be inflammatory, even if the conservatives aren’t out to get him in the way they’re out to get Christopher.” Boyce took Santo Santoro’s Senate spot in Queensland in a coup for the moderate forces in the Queensland Liberal Party. In current circumstances, the promotion of either would be seen as yet another insult to the party conservatives. They’re still smarting from the somewhat premature execution of Bernardi yesterday, whose old golf anecdote drew an anguished response from Pyne that he had been a Liberal supporter since, well, in utero.

It’s not clear there are any good conservative replacements in the Senate. There are Costello-allied replacements, like Mitch Fifield, but they may not automatically make the conservatives any less grumpy.

Turnbull could, if he was so minded, draw on the example of the man who conspicuously praised him last night, his fellow New South Welshman John Howard. During Howard’s first stint as leader in the 1980s, he led an extermination campaign against party moderates, and their complaints only encouraged him as he supported the removal of liberal MPs in favour of hardliners like the Kemp brothers and Peter Costello. More likely, given that Peter Costello still lurks, Turnbull will play it safe. Coalition sources suggested that, given Senate Estimates are on next week, Turnbull would let things cool down before announcing a replacement. No one ever died from the lack of a shadow Parliamentary Secretary.

But this week’s shambles keeps coming back to structural issues within the Liberal Party. What’s going on within the Liberals — the ideological divide, the personal animosities, the state-based rivalries — are exactly the sort of thing that go on inside the ALP. But the ALP has a factional structure that can deal with them, at least most of the time. It isn’t perfect, and it serves as a showcase for party divisions, but tensions can be resolved effectively if not amicably. No one says Kevin Rudd and Julia Gillard are close friends or ideological soulmates, but they seem to make a reasonable combination.

So as it stands, Malcolm Turnbull has to deal not merely with Peter Costello’s apparent determination to cause trouble, and the conflict between progressives and conservatives, but also rivalry between NSW and Victoria (John Howard had to deal with that too in the 1980s, courtesy of John Elliott), not to mention the likely disenchantment among West Australians about Julie Bishop’s treatment, and issues between the party hierarchy and the Parliamentary Party. Oh, and personal feuds.

And Barnaby Joyce hasn’t even had a chance to cross the floor yet this year.

The result is that virtually everything is seen through the prism of party instability. Tony Abbott — another discontented soul — yet again opened his mouth yesterday, but this time it was actually on his own portfolio, and it was the eminently sensible point that given the cost of pension increases, maybe they should be targeted to the most needy first. Abbott’s sense of timing is notoriously bad, but his comments were immediately and unfairly portrayed as further Coalition division.

Turnbull’s brilliant but lacks judgement. The leaking of the petrol excise email last year, and the phone call to Costello this week, suggests someone too clever by half, a man over-eager to shape perceptions in his own favour. And the sacking of Bernardi is being called an over-reaction, and it’s hard to argue with that. But it’s also clear that The Australian, which seems to find Turnbull’s progressive views objectionable, will continue to try to encourage speculation.

All of this comes back to Costello, who is the only possible leadership alternative and therefore the only hope for party conservatives and his own dwindling band of fans.

A bold leader might call a spill and offer Costello the final chance to show he’s got the ticker. He wouldn’t, and that’d be the end of him even for a party apparently loathe to criticise its most selfish member.