Coach leaves bench to sit in the stands.

[Ref_in_Alberta]

just to hi-light the FIBA rule...

Rule Three - Teams (OFFICIAL BASKETBALL RULES 2008)

Art 4. Teams

4.2 Rule
4.2.1 Each team shall consist of:
• No more than twelve (12) team members entitled to play, including a captain.
• A coach and, if a team wishes, an assistant coach.
• A maximum of five (5) team followers who may sit on the team bench and have
special responsibilities, e.g. manager, doctor, physiotherapist, statistician,
interpreter, etc.

Art. 7 Coaches: Duties and powers

7.3 The coaches and assistant coaches (as well as the substitutes, excluded players and team followers) are the only persons permitted to be and to remain within their team bench area, unless otherwise stated in these rules.

7.4 The coach and the assistant coach may go to the scorer’s table during the game to obtain statistical information only when the ball becomes dead and the game clock is stopped.

7.6 If there is an assistant coach his name must be entered on the scoresheet before the beginning of the game (his signature is not necessary). He shall assume all duties and powers of the coach if, for any reason, the coach is unable to continue.

So with the above under FIBA rules the only time an assistant coach may leave the team bench area legally is in 7.4. The AC in the stands would be a violation of the rules and should be dealt with accordingly.

Warn first & whack if the behavior continues.