No doubt the RN was told to dispatch a battleship so we could be seen to doing our bit to help, all about politics. At that point the First Sea Lord needs to tell his polticial masters the effect that will have, lack of coverage in Falklands, risks incurred, and they make the decision yea or nea.
As for MPA, they are probably the French, who traditionally operate in that part of the world. This stikes me as an ideal MPA scenario, certainly in the deeper water, searching large areas of ocean rapidly and calling in naval assets when required.
Why no Nimrods? Simple because there aren't enough to go around. And we will only get 9 MRA4s to replace 20 odd MR2s.
So, if you are going to use priracy as a reason to increase the destroyer/frigate fleet, which the admiralty traded off against the carrier purchase, then please get the RAF another 11 MRA4s while you are at it....
I wish you luck, but would suggest banging your head against a brick wall would be more productive in the long term...