Nationalist Kvetch entirely, those are Brits on the island, not just British citizens, full on ethnically British Islanders who've lived there almost since anyone knew the islands were there to begin with.

When polled they overwhelmingly voted in favor of remaining with the UK

Falklands are as British as black pudding and the royal corgis. Argentina just keeps pressing the claim because it makes a good nationalist distraction whenever right wing nutcases inevitably prove to be completely incompetent.

Also, any attempt to link it with some overarching notion of decolonization is complete bunk, the islands were uninhabited before they were discovered it's only colonialism if you think the very concept of an exclave is colonialist because that's in effect what they are, a very far removed exclave.