If you don't know what those "fans" were saying to him, then how do you know if the gesture was justified?
And no, I'm not one of these people that suddenly thinks players should just be basketball robots and above it all. That was NEVER the case in the past and it's not the case now. Fans can't show up and say anything they want and expect players to not react.
Some fans definitely deserve some run into the stands Ron Artest treatment.