He'd have stayed a hero, even later - like many who continue to be heroes in older age. He was already very different in disposition and willingness to do stuff for good compared to his Reddit peers.

In the real world the quote mostly applies to people who were already merely superificially good younger. Some corrupt politician which once was participating in the student movement (when it was fashionable and advantageous for them), some billionaire founder that paid lip service to "don't be evil" when their company was just growing and needed good PR, etc.

People who were geniunely good, and not just doing token "good gestures", tend to stay good.