The angle calculation was simply based on the need to deny minimum clear runway width for use by Argie Mirages. The stick spacing dictated the gap between craters and the calculation of attack angle was designed to prevent leaving a gap wide enough to land or take off. In the event only the first bomb of the stick hit the runway so the maths were incidental.
Naval Eye is quite wrong in that, as a result of the first Vulcan attack, fast jets were not based at Stanley for the duration of the conflict. Had they been, Sharkey Ward and all his mates would have not enjoyed air superiority and the outcome of the war would have been quite different. It was not possible to deny Stanley airfield to Pucara or C-130 but it was essential to stop the Argies using it for fast jets.
Naval Eye also needs to take on board the fact that no air-to-air weapons were carried by the Argies to the Falklands after their first offensive missions. If the raids had been escorted the air-to-air score would have been different.
The Vulcan raids, although far from perfect in terms of accuracy, enabled the Harriers to operate with no opposition. That in no way is intended to suggest that they did not do an outstanding job but merely to put into perspective the effectiveness of the prodigeous effort it took to get the Vulcan to the target and back.