But if the airfield is wiped out they don't need any LPDs. This is not going to be an opposed landing.
They could just take some normal civilian ships and use them for transporting their troops.
An Unopposed Landing?
What would be doing the four thousand British (Army/RAF/Royal Navy...) deployed in the islands? Drinking tea?
Waylander the Argentinians would have to destroy not only the airfield of Mount Pleasant, the also would need the neutralization of the Airport of Port Stanley. And even if the do that, remain to be seen the capacity of the other two unprepared airstrips in the islands to ressuply ops with C-130. Obviously these could be used by any Harrier GR.7/9 ferried directly with air refuelling support or after a stop in Ascension Island.
But if they destroy or render useless the two long airtrips (Mount Pleasant & Port Stanley), they eliminate their own possibility of deployment for the jets of the FAA, and they would be renouncing to ferry troops and supplies by air.
Also they woud have to eliminate the South Atlantic Patrol Task, if they not, the civilian ships and the Argentinian Navy ships without SAMs (and only the four Meko 360 have the Aspides) would be sitting ducks for the Type 42 that navigates those water permanently.
Another question is the use of civilian ships to ferry troops to the Falklands. If they do that, they will be restricted to disembark them in port. That is an important problem, any port damage (by demolition charges) or a resolute opossition from the garrison and all the operation may blow up in your hands. You know the Argentinian government is not a dictatiorship, death of civilians crews would be a big bad thing to the support of the Argentinians of a new Falklands adventure.
Oh, and you can forget a clean beach landing like they do in the 82, this time they would be restricted to small forces deploys on beaches by zodiacs ad-maximun, and civilians ships docking in port.
Another problem would be achieve the surprise element on any operation of this magnitude against the Falklands when
every Argentinian military movement or exercise that include more than twenty (20) airplanes or four (4) ships in the area delimited by the Treaty of Madrid, must be notified to the British government with sufficient advance to able the British authorities to send observers (and they may be people, aircrafts or ships) to verify the purposes and realisation of the exercises. The smaller clue of a violation of the treaty discovered by the MI-6 or any allied intelligence service... And they would have many oportunities to found evidences, because to enlist and prepare civilian ships, organize the ground forces, transfer the aircrafts to the southern air bases, etc... to mount a serious thing, would require some time and also would be very suspicious troops, aircrafts and supplies movements of the Argentinian war assets previously to the attack.
I will repeat once again. Any Falklands adventure, "a la Malvinas '82", is only a fantasy dream, with the actual situation of the Argentinian Armed Forces.