A lot of over-reaction here. Harrell was on the ground, was getting swiped at when he no longer had the ball, got up, threw a half punch/glorifed closed-fist push, practically whiffed and was pulled away by his teammates. God only knows what happened to the ref here. The slow mo shows the punch didn't come close to touching him. The only contact was him trying to grab Harrell to break things up.
Basketball is a physical sport. Tempers will flare from time to time. It's not like he sucker-punched someone that wasn't looking or went into the stands. Throw him out of the game if you want but this does not warrant a suspension in my book.