What he did was correct then.

The British repelled an invader, the Belgrano was a legitimate target, even the Captain of the Belgrano said so
After the war.

If the Argies didn't want the carp kicked out of them, they shouldn't have invaded.

The Brits should have bombed Argentina mainland, including the capital.

And apart from a few rat bags, the whole of The Uk was behind the war effort.
Even the unions stopped striking and pulled their weight.