Christina is riding the wave of re-election from earlier this year but her country is divided and has an economy that is going down the tubes (again). Uruguayans don't actually like the Argentines that much and have probably agreed to this for the sake of a quiet life.
Interestingly, Uruguay has its own island dispute with Argentina over an island in the River Plate which the Argies decided would be better off flying their flag instead of Uruguay's.
Saw someone who purported to be an Argentine military pilot wearing a Malvinas badge (complete with Falklands map) on his arm this year - haven't laughed so hard for ages.