Still don't understand. Why was he playing a second ball off a tee?
He borrowed a ball from another player on the tee, and was able to substitute one of his own and return it without finishing the hole, despite it becoming his ball in play because he had a relief situation.
Under the previous rules he would have had to play it until the end of the hole (as you know).
The end. 🤗
(News to some, old news to some)