Yes, if you define sz as something one never recovers from, then anyone who has recovered didn't have it - by definition. But then you'd only know if someone has sz in retrospect as there's no way to know if the person in front you at the moment has it or not because you don't have a crystal ball to see if they'll recover. So, it's stupid to tell someone they have a condition from which they'll never recover. You'd just have to wait until they do or don't recover. It's useless, and no predictions can be made based on it. I can guarantee you, though, that if you go around telling people they'll never recover, and you have the kind of authority that makes them believe you, there's a much better chance they'll never recover. It becomes a self-fulfilling prophecy.