You're close, but not quite right: "The Exclusion Zone is one of the most heatedly contested places on Ariadna. The term refers to all territories on the main continent that have not yet been colonised by Ariadnans and includes more than half of the planet," (emphasis mine). While it's true that the language is not clear (the term is used confusingly in many places) it appears to be intended that there is a separation between the Exclusion Zone (which is protected from mining and other economic exploitation) and the Outer Crescent (which is not protected). This makes the existence of Corporate strip mining in the areas which they can access match with the rest of the setting. But I do agree that parts of this section could be MUCH clearer.
