As Argentina recently tried to create problems for the oil companies exploring in Falklands waters by saying that bank loans to the companies were illegal, I think this might be HMG's way of saying 'two can play at that game'.
Its a warning shot to say that if Argentina starts playing games with the banking system, the UK can do so as well...
Perhaps the point is that when they don't pay up, this puts them most satisfactorily in the poo as a dafaulter and puts them on the wrong side of the iMF when they come crawling for a bailout when the Args' fairy-tale economics finally fail.
Some of this money will have been spent in Britain on their first Type42, Sea Dart missiles, Lynx helo etc plus licence to build the other 42, so just for once a bit of foreign aid did get spent here. Otherwise i have no doubt the French would have obliged by refitting the Arg fleet.
Pity we can't charge them the equivalent of barrack damages for the mess they made in FI, let alone the cost of kicking them out. Besides we saved them the refit costs of the Belgrano, decent of us. So send bill for 3 no Mk8** torpedoes too.