Imagine you find an uninhabited, undiscovered and unclaimed bit of land. You decide to build a house there because its a nice spot and nobody else is around for you to disturb. You call together your friends and family members and you all spend a lot of time, effort and money on building a lovely house, which you live happily for a short time.
Then, one day a stranger comes to your house and tells you that he has recently purchased that bit of land from the local government, and now owns not only the land but everything on it, including your house. He wants you all to leave immediately so he can live in it instead.
That is not 'morally right', nor is it meritocratic, because the person who contributed precisely nothing to the development of the house is the one who gets to live in it.
This reminds me of a bit of a side quest from Jade Empire.
Old Mother Kwan built a Teahouse and had been running it for decades, then Creative Yukong appears out of nowhere with an Imperial Writ (that he forged) that says he and his family owns the land, and thus everything on it, and had for generations, thus stealing the Teahouse from Kwan and he intended to turn it into a Tavern.
The quest is proving that he forged the writ to steal the business, or allowing him to bribe you to look the other way.
Ok, expanding this beyond the fridge analogy; if I was up on what appears to me to be a deserted island and build a house on it and live there peacefully, only to later find out that the island is privately owned when the owner shows up, the owner of the island has every right in the world to kick me off that island. Doesn't matter if he's using it or not, doesn't matter if he only shows up there once every ten years. It's his property and if he doesn't want me on it, I don't have a right to be there.
I don't know. I just think that when you're imposing on someone else's hospitality, their opinion of what is and isn't reasonable matters a little bit more than yours does.
But then this begs the question of, privately owned as in it was newly discovered and they just purchased colonization rights only to find out we're already colonized there, and without the legal system, who then is in the right?
No one actually owned the planet. It's not part of any government, save for those already there, and the only thing the "locals" quote unquote have going for them is that they went through legal channels to purchase rights to colonize a system no one knew existed until after it had already been colonized by someone else, and we found it before they did, so are we in the wrong because they bought the rights, or are they in the wrong because they had a rush-to-judgement and bought the rights to colonize the system before finding out themselves if it already had residents?
There is no black and white choice in such a scenario. They did purchase the rights, but they did so before finding out that there already were residents. We, hypothetically speaking, are the newcomers, but we settled and colonized a system even before they knew it existed, and possibly the survival of our race depends on the success of the colony.
It's a situation where one side gives the other concessions and leave peacefully, they both colonize and try not to fight with each other and share resources and land, because, let's face it, it's a planet, not a small country, or they fight for the right to keep the system for themselves.