Coach leaves bench to sit in the stands.

[Adam]

If he decides to be a fan, he's out of my jurisdiction as far as shouting instructions to his players. In JV games, you hear the varsity coaches do it all the time. Once he joins the huddle, though, I'll warn the HC if I'm feeling generous.

You have two options.
1. Have the fan removed for entering the court.
2. Charge a T to the assistant coach for leaving the bench (the box is irrelevant for an assistant coach); don't forget to give the HC his indirect.