I have no problems with someone taking high moral grounds and getting emotional about it.
Airlines who write commercial contracts with a customer constraining or forcing the use of some segments might be punished by gods. In some cases, gods could be courts. But the major god is the marketplace. I assume that carnarvon votes with his feet and privileges airlines offering one-way tickets at "reasonable' price, as defined above. If a sufficient number of customers adopt the same attitude, the marketplace will sanction other airlines. And that does happen in markets where LCCs compete heavily with legacy airlines. Free competition comes to the help of morality as expressed by carnarvon.
But the differentiation of what is good (or right) and what is bad (or wrong) differs across individuals. Personally, I fully understand that running an airline is a business and that their pricing structure can be complex in trying to segment markets and customers. I do not find it immoral. But I agree with carnarvon that the trend caused by competition is toward more flexible segment pricing, at least in some markets/regions.