Well acschually oxygen is a corrosive chemical and probably damages your lungs (since that's the tissue that comes in most contact with it). And also the Great Oxydation Event is probably one of the greatest - if not the greatest - mass extinction of all times, so ...
Well it's literally Pocahontas in space so more obvious comparison is to the colonialism. They could grow gardens and farms while destroying the natives, the movie would have been the same.
It was just one line of dialog, but the sequel did mention that the company is expanding from just resource extraction to selling settlements to the wealthiest who are fleeing a dying earth