To be honest Cyouskin was trying to be quite civil for a long time. It was the other posters who started to attack them directly which probably pushed them to say things they probably shouldn’t have.
You have to remember we are all human. MVPs are no different from the rest of us players.
Each of us would probably bite back eventually given the right provoking.
Feel free to report them if you feel their conduct was unjust, but just be sure you aren’t treating them differently because they are green, and ensure that you report others for equally reportable conduct.