Right on some things (War on Iraq, media bias on Isreal & Palestine) - wrong on other things (ie, this).
Only a few fanatics agree it shouldn't be part of the UK - even a large group of Argentine intellectuals argue it should remain British as the rights to self determination is paramount.
The other point being historically they don't have a valid claim, Spanish colonialist don't have some magical superiority suddenly to British colonialists.
If it was in the indigenous people of South America asking for it back I'd be inclined to at least take it seriously - maybe they assume nobody knows the history.
I mean, I'm all for giving back land which has been historically stolen - but in this case it had no indigenous population - so it simply doesn't apply - hell even the Dutch have a better claim (IIRC).