Top Gear is like the mafia - they'll have enough connections to get the cars out of the country. Not that the anyone on the TG production staff really cares; the cars are essentially expendable for the efforts of the production.
Heck, even if they did get the cars back, what's going to happen? Maybe one will be stuffed on a plinth in the studio, or shown at a TG show for a few weeks - after which it will be relegated to rotting away in the Top Gear dead lot at the Dunsfold Aerodrome.
Let the cars rot away in Argentina - where there's a better chance some official with a hankering for a '71-73 Mustang will pull a few strings to make it his or her own little war prize.
Imagine being the guy who sold this thinking it was going to a good home.
From some early discussions, which I can't seem to find on Google now, TG painted it up. Far as I know, it was in primer when offered for sale stateside. The fellow who sold it to them (who found out later - car was sold with a non-disclosure agreement) did contact them later in protest.
It looks good here, but there's a possibility it might be a painted rustbucket. If so, I'll admit that I wouldn't mind doing what Hammond is doing in this photo with a rusted-out '71-73 - with exception to the snow flying up into the car through the floorboards. Looks like fun.
It also proves that Mad Max would have been better with a '71 Mustang! (ducks for cover as I get pelted with tires from our Aussie buddies).
-Kurt