That's not at all clear from the story.
"Hinkle's son played defensive end for most of the season"
Could have played offense & defense in earlier games. In fact, no coach with Owens' experience would take a shot in the dark by switching a pure defensive end to sticking him on offense in a critical game, without that player having playbooked, scrimmaged, and previously played that position on offense.
Correct. Which was fine with the commissioner. His concern was that his son play defense every minute of every game. If the coaches ALSO used him on offense, that was their call.
Apparently, in the last game,the coaches played him on offense instead of defense. The first time they did that all season.