Cleveland Cavaliers refuses to respect the National Anthem

[jwwashburn]

Dion Waiters informs NEOMG that he is a Muslim and plans to skip national anthems | cleveland.com

In the NBA Rules Book I found:
In the Comments On The Rules section:

H. PLAYER/TEAM CONDUCT AND DRESS
(1) Each player when introduced, prior to the game, must be uniformly dressed.
(2) Players, coaches and trainers are to stand and line up in a dignified posture along
the sidelines or on the foul line during the playing of the National Anthem.

Is this an actual rule? What is the penalty? Would it be a Technical Foul? I do not see a remedy for violating this.