The bank's argument was all too familiar - it has to pay its staff the bonuses because it has a legal obligation to do so. We heard the same thing from the UK banks when taxpayer outrage was at its height. Except Lenihan told the bank's board that, if it paid the bonuses, he'd pull its state aid. And voila, all of a sudden it wasn't so illegal to scrap the bonuses.
AIB, of course, came to the quick judgment that no-one would get paid anything if it was insolvent, which is what it would be if the state somehow managed to claw back the 3 billion it has already laid out and stopped the many more billions due from the IMF and the EU.
The sudden turnaround across the Irish Sea is set to bring flashbacks to the bad old days of 2009 at Gogarburn. One of the achievements of Stephen Hester, chief executive of government-bailed-out Royal Bank of Scotland, was to convince his new owners at the Treasury that stamping out bonuses would kill the bank's golden-egg-laying goose.
Instead, both RBS and Lloyds Banking Group negotiated a compromise - from here on in, bonuses would be delayed for three years to ensure staff weren't just filling their boots at the expense of the bank's capital, and would be paid in shares that would better reflect the impact of their performance on the bottom line.
The compromise meant RBS could keep pay in line with its competitors, slowing if not completely preventing a haemorrhage of staff to other banks.
Letting the bank run along comparable commercial terms would be the only way to get the tax payer's 45bn back - eventually.
The much bigger UK banks clearly had a stronger negotiating position than their Irish counterparts. For one, AIB is not a major international player. If bankers at AIB figure they can find a job that pays better in Dublin, then most will probably shrug and say best of luck to them.
The numbers actually aren't really that big - 34m averages about to 13,600 per employee that were due a cheque. But clearly the Irish realise it just won't fly to allow anyone to be paid on the back of performance in 2008, when loans funding a ridiculously overheated property market were still being sold. It will be a brass-necked executive indeed who tries to take AIB to court to recover contractual bonus payments.
But what is troubling for RBS and Lloyds is that Lenihan's gambit will reignite the debate in the UK. The touch paper has been prepared by regulators.On Monday, Michel Barnier, the EU financial services chief, warned that he would not be "blackmailed" by senior bankers threatening to move their headquarters or top staff to less restrictive markets, while his UK counterpart, Hector Sants, backed him up.
Being a banker in Europe is set to become a much less lucrative activity and it is long overdue a "deleveraging". But it remains to be seen whether anyone will stick around to do the job.
Wikileaks whets appetite for knowing rights and wrongs
wHAT'S the difference between a banker who made "very big bad business judgments" and one who failed in his -because it is invariably a "he" - fiduciary duty? Arguably, the latter could be sued while the former just has egg on his face.
The latest Wikileak concerning Sir Philip Hampton, the chairman of RBS, reports that he told some American politicians that the bank's board had "failed" in their duty to shareholders.
Yet it is not the first time Hampton has shared his dim view of the actions of Sir Fred Goodwin et al - in an interview just days before the leak, he described the takeover of ABN Amro as a "very big bad business judgment".
Even my aunties know that the ABN deal was as dodgy, in retrospect, as a 3 note. And this is a common reaction to some of the Wikileaks revelations; they seem to come straight from the notepad headed the "Department of the Bleeding Obvious".
But the trouble is the leak comes just after the Financial Services Authority let the RBS board away with a mild ticking off over the ABN deal, ruling that, while RBS had made bad decisions, it had acted with "integrity".
Of course, we don't know how or why the FSA report - written by accountancy firm Price-waterhouseCoopers - came to these conclusions, because the public was banned from seeing it. Nothing to see here people, move on, the FSA effectively said.
But the Hampton leak has served to light a fire under Andrew Tyrie, the chairman of Treasury select committee, who has written to FSA chairman Lord Turner demanding the report be published.
Too bad no-one at PWC or the FSA will be sending a redacted copy to Wikileaks.