Sam Dastyari must have set a new record for apologies. When the besieged Labor senator finally faced the media in Sydney on Tuesday, the sorrys came thick and fast.

Dastyari is under excruciating pressure over his fundraising habits for very good reason.

Accepting money from a Chinese donor to pay out an overspend in personal entitlements, and a legal bill, suggests you don’t know where to draw important lines.

Going an extra step of dialling down criticism of China’s aggressive posture in the South China Sea – if that’s what he did (it wasn’t entirely clear at the press conference – he held out the options that he misspoke or was misquoted) puts a significant question mark over his position on the Labor frontbench.

Bill Shorten is backing his New South Wales colleague, reasoning he deserves a second chance, and Dastyari said on Monday he hadn’t been asked to resign, nor had he offered to wander off into the sunset to shut down a persistent distraction for his leader.

Dastyari is a significant institutional player in Labor’s ranks, despite Shorten’s efforts to portray him as a young pup, who needs some training up. His position in the internal power structure affords him a measure of protection when trouble strikes.

But regardless of how this story ultimately ends, whether he toughs it out, or whether he doesn’t, we can thank Dastyari for the following things.

The first is, without even being conscious of it, senior players in the Coalition have lined up to make a compelling public case over the past few days that there is no such thing as money for nothing in politics.

There has been a roster of frontbenchers, from the prime minister down, standing up with loudhailers to argue that Dastyari’s conduct is an example of “cash for comment”.

Let’s just think about this for a couple of minutes. The declared conduct from Dastyari involves payment of a $1,670.82 overspend and a $5,000 legal bill. For most Australians, me included, this is a lot of money.

But, viewed in the context of all the money sloshing around in federal politics, the money these folks chase as a matter of routine, it’s a drop in the ocean.

So let’s accept the government’s logic at face value and persist with it.

If one Labor senator can be influenced by a comparatively modest sum, there’s an obvious follow-up question: what does millions buy you? Presumably more than $5,000-odd buys you.

Perhaps it leads, for example, to Labor having to work for the best part of a year to try and herd cats on the China free-trade deal – the agreement the trade union movement didn’t like.

Perhaps, as some frank Coalition MPs have avowed publicly, what donors think becomes a live issue when the government is trying to formulate a superannuation policy that curbs tax breaks for high income earners.

One could suggest that given circumstantial evidence is being deployed against Dastyari, maybe there is a double standard at play.

These are just two recent examples, using the government’s smoking gun logic, that might lead reasonable people to form a conclusion that millions from trade unions and from corporates to Labor and the Coalition may not be abstract bursts of charity.

So again, let’s step through this, firmly in possession of the government’s logic.

Dastyari has done us all a favour by highlighting one problem in the current system: the capacity for foreign interests to try and assert influence in our democracy.

But China’s assertion of soft power isn’t the only problem. By muscling up aggressively against Dastyari, the government has thrown open the door on a wider question, about institutional influence more generally.

Institutional backers do influence policy outcomes in Canberra – it’s just not something the major political parties generally like to acknowledge in polite company, lest people form a conclusion that their representative democracy isn’t about them.

So when the attorney general, George Brandis, goes on morning radio and argues reform of the donations regime is a “different conversation” from the travails of Dastyari – he is dead wrong.

Hiding behind a construction that this is an “unconventional” donation just doesn’t cut it.

If you’ve got a problem with what Dastyari did – and we all should – you have a problem with institutional influence in Australian politics and, once you open that conversation up, it’s impossible to build a rhetorical firewalls. You can’t bend the conversation to suit your political convenience.

So, where to from here?

It is entirely possible that the broad-ranging policy conversation we absolutely need to have will founder where it so often does, in the territory of self-interest. But there are some promising signs and I think we need to look through the distractions, grab them and drive them home.

Labor says it will ban foreign donations, require near real-time disclosure of donations, lower the thresholds for disclosure and support increased public funding.

It’s not nearly enough but it’s a start. The Greens would support those things and more. Promisingly, various Coalition folks are also busting through the “all about Sam” political containment line.

Cory Bernardi says donations should be limited to people on the Australian electoral roll – a change that would sweep out the institutional and foreign money – and a position in synchronicity with the prime minister’s previously expressed views.

Two cabinet ministers, Steve Ciobo and Darren Chester, have sent positive signals about banning foreign donations and about continuous disclosure in the past 24 hours.

Malcolm Turnbull is on the public record supporting change to the disclosure regime and is a prime minister in need of a substantial win. So why not take control of this issue and make a meaningful downpayment on change?

The choice is stark.

We can either indulge in a bout of hand-wringing and a flurry of hurled off headlines to get us all through another, febrile, waterfall news cycle – or the parliament, led by the prime minister, at the request of the voters who absolutely deserve a stake in a healthy system, can knuckle down and do something about it.

• This story was amended on 7 September 2016 to correct the amount of Dastyari’s legal bill.