Because I would have to stay in La Plata for the next few months and would be reported to Interpol as an official victim and will have to stay in Argentina to defend myself, if not the police in my country would go look for me and I would be arrested at the border.

wtf..... no wonder nothing works over there.

and my passport was thrown back to me by the robber

lol, good guy robber, takes cash and gives back passport. :P