Disgraceful. They should throw the ball at him for that.
No, but in reality it's classed as violent conduct on the pitch. And before you moan about that, just stop and think where you would draw the line and decide what was violent conduct if you don't think that that was.
I am pretty sure it is even written in the laws that if a player throws the ball at another player it is a straight red. So the ref had no choice whether you or I or the ref think it is correct or not.