Finally one barnacle has been removed from the Abbott Government, and just in time for Christmas: Arthur Sinodinos is gone as assistant treasurer, writes Mungo MacCallum.

After months of procrastination, Arthur Sinodinos has been informed that his resignation as assistant treasurer has been accepted, whether it was offered or not. And to seal the compact, the resignation was leaked immediately, just in case there could be any second thoughts.

The embattled senator, it will be recalled, was invited to the ICAC to shed some light on the shenanigans involving Australian Water Holdings (AWH), the dodgy company promoted by disgraced entrepreneur Nick Di Girolamo and his ally Eddie Obeid. The Commission was particularly interested in the fact that large sums of money had been remitted from the firm to the federal Liberal Party, and felt that Sinodinos, in his joint role of AWH director and Liberal Party Treasurer, might be able to help.

But alas, Sinodinos knew nothing - an important qualification for a front bench position within the Abbott Government. And he is convinced that, in the end, he will be vindicated and indeed reinstated. He may be right: the only certain things against him are plausible denial and insensate greed, the latter from the hope and expectation of a multi-million dollar windfall from a shonky deal he was pushing on behalf of AWH. As far as his political colleagues are concerned, these are certainly not serious offences - indeed, they are more matters for congratulation.

But in the meantime Josh Frydenberg takes over as back up for Joe Hockey, recently crowned in the polls as the worst treasurer in a generation: something of a poisoned chalice, but a chalice nonetheless - prospective ministers can't be choosers. And Sussan Ley gains promotion, but mainly through headlines reporting her as a second token woman as female company for Julie Bishop - Abbott has played the gender card again. There is some movement among the junior ranks, but at the top it looks more like a case of rearranging the deckchairs on the Titanic. The big loser is David Johnston, dumped in spite of Abbott's fulsome (in the correct sense of the word) praise just a fortnight ago. Kevin Andrews and Peter Dutton have been moved to Johnston's political death zone of Defence and Scott Morrison's demolition area of Immigration respectively and Morrison himself gets Social Security with an opportunity to prove that he can be as brutal with welfare recipients as he has been with refugees. And so the ship founders on.

Sinodinos must be hoping to emulate Julia Gillard, who has now been officially cleared not only of criminal conduct but also of knowledge of criminality by the Heydon Royal Commission into trade union corruption. And this, in the words of The Australian's chief prosecutor Hedley Thomas, is where the Australian Workers Union slush fund saga reaches its natural end.

Or at least where it should end. But Thomas, who has pursued the former prime minister with an obsessive diligence worthy of a better cause, is still reluctant to let it go. There will be great differences of opinion, he avers, among voters, lawyers, politicians and journalists about Gillard's role and knowledge. Well, among some journalists and politicians, certainly, and perhaps even among some lawyers. But among the voters? I very much doubt it.

If they considered the 18-year-old case at all, it was probably in the context of a stitch-up by the Abbott Government. The Royal Commission into the unions was in itself seen as something of a witch hunt used to damage the ALP, but at least that could be justified in the light of thuggery and bullying in the workplaces - although it also needs to be said that many of the employers were willing accomplices in paying out the money allegedly extorted. After all, they could, and usually would, pass the cost on to their customers.

But to attempt to embroil Gillard in the process was naked spite and vindictiveness. And after all the sound and fury, all the accusations and innuendo, it failed: the worst Gillard was found guilty of was a bit of "casual and haphazard" work as a young solicitor - a bit of legal jaywalking which, she admits, she would, in retrospect like to have had her time again. No doubt she would; no doubt she now regrets hooking up with Bruce Wilson, who was the instigator of the apparently illegal slush fund, in the first place. But a romantic misjudgement is hardly a criminal offence either.

Gillard also says that she would like and apology from Abbott and his ministers who, under parliamentary privilege, accused her of committing a crime. She is unlikely to get one, which might be a matter of premonitory concern to Sinodinos. After all, if political payback is to be the norm, what is to prevent a future Labor government from setting up its own Royal Commission into Liberal Party rorts and fronts to launder political donations which, the ICAC found, were administered during the time Sinodinos was the Party's federal treasurer?

And we cannot finish the week, or indeed the year, without a mention of the Martin Place siege. For my money, the police behaved impeccably. All too often they can be impetuous, even reckless: a matter of shoot first and ask questions afterwards, and if there any accusation of impropriety, lock the bastards up and throw away the key. But this time, they did it by the book: secure the area and try to wait it out. And for 16 long hours, it seemed to work.

In the end, of course, it ended in tragedy - but it probably always would have. At least the cops did their level best. If they had stormed the place immediately it might have come to a climax sooner, but it would almost certainly have produced the same result, if not a worse one.

There is now, inevitably, a series of inquiries and soul-searching, including arguments about whether or not the gunman was really a terrorist, and whether he was insane. Frankly, it hardly matters. He was an evil and dangerous man who was never going to become reconciled with the country in which he had chosen to live. Whatever his motives and psychology, he was always going to end badly - as it does with all of those nurturing hatred, bigotry, delusion and a lack of human empathy.

For all of them, bah humbug. For the rest of us, season's greetings: I'll ride with you.

Mungo Wentworth MacCallum is a political journalist and commentator. View his full profile here.