Stu Jackson, NBA executive vice president of basketball operations, explained his decision in an e-mail to the Globe, also laying out why Richardson was fined rather than also losing a game.
"Garnett was suspended for throwing an elbow that struck the head of Richardson," Jackson wrote. "This action is analogous to a player throwing a punch that connects. By rule a player [who] swings his hand (with an open or closed fist), whether or not the hand connects, will be automatically suspended for a minimum of one game."
"The foregoing also applies to comparable methods of striking or attempting to strike another player (e.g., “head butting” or elbowing above the shoulders). This is the reason for his suspension."
"Richardson's actions played a role by precipitating the altercation that followed (e.g. verbal exchange with Garnett)," Jackson said. "These actions warranted a fine. Also besides Richardson's verbal exchange, his grabbing of Garnett was considered. However, both these actions warrranted a fine, not a suspension."