Yes, well, I have the power to do a lot of things that I don't have the right to do. Waging a war of conquest is immoral, you have no right to do it, and you have no right to any land you gained from it.

And yes, that ultimately implies that all land ownership is unrightful and illegitimate. I'm with Gerrard Winstanley: private land ownership was the original sin, and communities holding land in common is the first step to redemption.