I looked at the definition of the meaning of greedy and found the following
"Excessively desirous of acquiring or possessing, especially wishing to possess more than what one needs or deserves. ".
In order to determin whether the landlord is being greedy you would need to know all the costs and legal agreements surrounding the property being rented.
For instance, Does the landlord make an excessive profit ?, and also, does the landlord have expenses which they themselves have to pay in dollars, such as a mortgage or a higher landlord ?
Unless you have these facts you cant possibly say that the landlord is being greedy.
I never disagreed with your knowledge of Argentine law, but the word greedy is not relevant to whether they prefer to be paid in dollars or pesos.