This seems like an obvious situation. If you commit battery in public you will be charged. Sports players, public figures, celebrities, whatever they are should not exempt from anything that the normal person would face a penalty for. The fact that we have to ask ourselves if a sportsman should be punished is appealing.
He himself knew what he was doing was wrong. He admitted that he noticed his opponent was in discomfort; but he chose to not let go. The other guy even loss consciousness as a result. Suspending him from the games is justifiable in my opinion. If he wasn't penalized, It might give other players the impression that they can do the same.
Sporting events have a reputation to uphold. If a player were to become excessively violent, then he must be penalized for it. The fact that this behavior even took place is a great disgrace to the league, and a large blow to it's dignity. If the league wants to be viewed in a professional manner, it must also act in one.
The player who attacked his opposing teammate should be penalized for the attack. Although Aussie Rules Football is a rough sport in general, the fact that he choked his opponent is rather extreme. To not penalize him for the attack would set a precedent that could seem to promote this level of violence.