I would definitely be willing to use this as a guide to WP:WEIGHT and what countries to mention, but I have to point that no country backing the UK is mentioned which would leave the section looking a bit partisan. I'd say we should nonetheless try to source the statement mentioned above the Argentina has something to gain from raising the issue and the UK does not, which would explain the imbalance in opinions being voiced. As for the reduction of the section I note that much of it is being taken by the mentions of the UN and the USA which could easily be trimmed down. The re-naming of the section I disagree with, at least with the proposed one which is a clear violation of WP:NPOV. But this can be of course discussed.
I also present this article by the same source which mentions the positions of a lot more countries regarding the dispute, including Venezuela, Nicaragua, Russia and China. Regards.