For the purpose of PW service policy coverage and prolonging engine life this rating should be used, at the pilot's discretion, only when required to ensure safe flight. NOTHING ABOUT BEING RESTRICTED TO EMERGENCY SITUATION
Now this is a literary debate.If you cannot ensure safe flight without the use of MCT it could be termed emergency/abnormal. Your own quote if turned around means engine life is prolonged if you avoid use of MCT.Service policy coverage means you loose some maintenance credits if you indulge in MCT. It's evident that pilots use MCT with individual justifications. They will continue to do so unless their company tells them not to. So I think enough evidence is produced about what engine/ aircraft manufacturer says or wants. Time to move on.