Wow, That's inspiring. That was very considerate of you for your action. In his behalf, thank you. I suspect he/she would thank you too, if they knew how to contact you. I will watch for the same situation and try to mirror what you did.
Since this is a charging etiquette. From your low post count, I guess you are new to owning a Tesla? I hope I am wrong for your sake, but its been too common for a very long time at public chargers for non-Tesla owners to unplug Teslas seen charging. A few have been caught/seen. Of course no one can do anything/does anything to those folks. But its too common. Just so you know.