My point is just holding the ground is not enough to legally/ethically claim the land, especially if you’ve kicked out the people on said land that used to be there.

And since this didn’t happen on the Falklands, your point is completely asinine.

Self determination requires two things - the whole determination part, in case of the falklands the referendum held and overseen by international observers; and the means to uphold that self determination against those who would ignore it (in this case, argentina).