I think it depends on the circumstance and severity of someone's actions that deem them just, or unjust. It all depends on how the general public comes to view an individual based off a set of norms, which are governed by society. I'm certain a child molester is evil in my book, cut and dry. There's nothing disputable about that.
What is Master Xehanort trying to accomplish again? The revival of the Keyblade War was it? What's the price of this knowledge and power? And does the ends justify the means? How many worlds, or lives will be toyed with, or destroyed all for the sake of knowledge? Is Master Xehanort trying to make the worlds a better place? Either way, the KHverse will see Master Xehanort as an enemy in relative terms, so the immediate concern would be to stop him.