Slapping backboard

[Brian Watson]

If you boil his action down to the bottom line what do you have?

Slapping the board does not prevent an injury (like holding the rim), has no positive effect on the game, and cannot be ruled unintentional (like a whiffed block). I think it is a no-brainer, his action was obviously intentional and unsportsmanlike. If it is a heated game,and you let this go, it might be the trigger for bigger problems. Ring him up, and don't think twice.