It's alright in my opinion. No need to go over the top with it as if he cleaned the referee out or got caught on PEDs. It was a push at the end of the day, the more violent the action the more punishment you should get as with any walk of life, and this is on the lower end of physical behaviour.
It needed a stronger sanction than normal to make clear that if you are threatening to refs you will get a lengthy ban and I think this is a lengthy ban. 8 takes him out for most of the remainder of the season, it's not something he'll forget in a hurry.