Malcolm Turnbull had no option but to sack Stuart Robert for breaching ministerial standards, even though the advice from his department head suggested there were some grounds for leniency.

Martin Parkinson concluded that Robert had "acted inconsistently" with the code of ministerial conduct, but accepted the breach was unintended, did not involve Robert receiving financial benefit and did not directly relate to his ministerial duties.

That was the narrow, clinical judgment from a senior public servant. The political judgment was whether Robert's transgression was a sackable offence - and Turnbull confronted a mountain of evidence this week that it was.

That Robert believed he was acting in a private capacity when he met a Chinese minister and attended a signing ceremony in China in 2014 was beside the point. Naivety, of itself, is not punishable by removal.

The critical issues were what the Chinese government officials thought – and there is no doubt that Robert was seen as being in China in an official capacity - and whether Robert could be seen as using his position to assist the business interests of a mate.

The danger for Turnbull in allowing Robert to keep his job was the same danger that Tony Abbott ignored when it was revealed that Bronwyn Bishop caught that expensive chopper at taxpayers' expense to travel from Melbourne to Geelong to attend a Liberal party function.

It was that embarrassing details about Robert's relationship with his friend, Liberal Party donor Paul Marks, and his "private" trip to China would continue to trickle out and give Labor ammunition when Parliament resumes.

Now the Prime Minister is finalising his second reshuffle after less than five months in the job, with four new faces likely to be promoted. That affords an opportunity to promote talent from the backbench.

The damage of this affair has not been the loss of a junior minister with a subterranean profile (yes, another one), but the tensions and contradictions inside the government that have been exposed.

What was Barnaby Joyce thinking when, having just been voted in as National Party leader, he defied anyone to tell him what Robert had done wrong on Friday morning?

While Turnbull had no option but to act decisively, he faces three dangers over the short and medium term. The first is that he will have no choice but to sack future transgressors, having made plain that those who stuff up do not get a second chance.

The second is how he manages the tensions within the government that appear to be multi-faceted and are very likely to become entrenched.

The third is a deputy prime minister who doesn't appear to understand the practicalities of power.

Follow us on Twitter