MSPeconomist,
Some travel agencies in Argentina book tickets for local customers using installment payment plans where a downpayment is made and the rest of the money is due later (but commonly prior to travel AFAIK). I have seen this done for bookings (BA tickets being the outcome) for flights from EZE this year too, some of which included AA-operated flights. I don't recall seeing that for AA bookings for flights from EZE this year, but an installment payment plan for AA reservations would commonly have full payment due prior to ticketing too.
I wouldn't be surprised if the payment settlement arrangements between travel agencies and airlines may facilitate such practices, but I am not sure about that. Commonly, funds due for tickets are swept into escrow type settlement accounts prior to travel.
I am sure about the following from AA:
September 26, 2014
American Airlines has implemented sales restrictions for Argentina point-of-sale on our flights to/from Buenos Aires (EZE), Argentina. These sales restrictions do not apply to point-of-sale outside of Argentina.
Reservations can still be made or ticketed for travel on American and American codeshare (AA*/OA) flights for departures prior to:
84 days for flights departing EZE
90 days for flights arriving into EZE
Reservations cannot be made or ticketed for travel on American or American codeshare flights (AA*/OA) for departures more than:
84 days for flights departing EZE
90 days for flights arriving into EZE
American will not accept bookings on other airlines with Argentina point-of-sale.