Mr Timmerman has made a bit of a fool of himself (although, given his government's position, he presumably had no choice).
He's confirming that Argentina has no interest in what the islanders want and, in so doing, that the principle of self-determination (enshrined in UN policy on these areas) is something Argentina doesn't support. Once the referendum is done, the UK should go back to the UN for a new resolution telling the Argies to foxtrot oscar (assuming that the Falklanders vote to stay with us) on the basis of (a) the historical evidence of peaceful settlement for so long and (b) the freely expressed will of the people who live in the disputed territory.
Incidentally, one of the oddest things I've ever seen was in the museum in Stanley. There are Argentine propaganda leaflets, distributed after the invasion in April 1982, calling upon the islanders to rejoice in their liberation from the colonial oppressors.
I've often wondered whether that showed a delusional belief that the kelpers really were under the British heel. Hard to believe, but then hard to think of another reason for them!