What I said is that legitimacy is just a term used to disenfranchise rivaling states. States claim legitimacy, even though such a thing does not exist. Legitimacy was a thing from the nobles, when a child could be a legitimate heir or not.

The only real thing in existence is force. There are all kinds of reasons to claim legitimacy (all the factors I mentioned), but none of them decide legitimacy in essence, since legitimacy is not a thing.

ROK claimed legitimacy due to it being the state that had control in the region at first. But a reason to claim they were not legitimate was the fact the populace didn't support them. Both of these arguments are valid. None of them decide anything, because the world doesn't work that way. The only thing that matters is that ROK controlled the land at that time, the countries that recognized ROK supported them, but that the populace didn't support them at the time. Those are the facts that should be taken at face value. Of course its claims legitimacy. And of course DPRK challenged that legitimacy by arguing it did have the support of the people, however, it had to fight for control over the region, which was partly successful, and some countries recognized them. The facts were as they were, both claimed legitimacy, both had valid reasons to do so.

All the other countries or ideologies picked a side on the matter which was most beneficial to them and that is that. I just don't see the value as an individual to pick a side on the question of legitimacy. Looking at the measurable facts is much more useful.