You admit it's a mistake (bug) on Blizzard's part, and you take advantage of it. You agrre to the terms & conditions where taking advantage of a bug/exploit is not allowed (every time you download a patch/xpac)...yet you qq when Blizzard growls at you lol.

And the GM wasn't making notes on your account, he was making a note of the accounts involved...a list. it's pretty easy to figure out what is on that list, the names of your accounts and what exploit it was. As it was, you got dealt with nicely. The GM could have just instantly banned you for 3 hours while finding out what exactly you are doing and then issuing each account with an official warning. But instead he/she asked you to stop whilst taking note of the accounts involved (in case you decide to return an hour later doing the same thing I bet, so the next GM would know that you have already been warned not to do it, and would then proceed to escalate you to a perma ban)...

Let off pretty easily imo. I don't see how you can be angry at blizzard for this.