Grant is talking about the number of test explosion of nuclear weapons, not the number of weapons. He is also talking about the US, not the UK. So I think you missed the point.

Regarding the Falklands, the HMS Sheffield was scuttled in the South Atlantic. Since it had had nuclear weapon on board when it last sailed from the UK, many came to the conclusion, it was scuttled specifically to get rid of nuclear weapons which had been damaged when it was hit by an Argentine missile. But according to https://www.declassifieduk.org/uk-deployed-31-nuclear-weapons-during-falklands-war/

the Sheffield's nukes had been transfer to one of the larger ships, Hermes or Invincible for better protection. Furthermore, at Thatchers insistence, the nuke-bearing ship were keep outside of the Latin America Nuclear Weapon Free Zone which included waters surrounding the Falklands. From this I deduce that Prince Andrew was as safe from harm as the nukes!

What the cited article does not describe is where and how the ship-to-ship transfer was accomplished. Given that the Royal Navy refused to off-load the nukes at Ascension Island, they would not have been happy about doing a transfer at sea. Does anyone have more information on this?