Is pretending to be GM allowed? Or is this really GM?

I am new player on molten and this is paste from my first Stand of ancients. I was controlling Demolisher like I think was the best and he started blaming and saying me that he will BAN me. I have whining so I ignore people like that, but was he really game master or is it OK to pretend to be one? Since that seriously made me wanna stop playing this game if game masters are like that.

You will see a <Blizz> icon if it's a GM. Read http://forum.warmane.com/showthread....orting-Players to report him.

Thanks for quick reply.