So by your logic whenever players form a raid to go kill Garrosh, GMs should seize control of him and bitchsmack them down? Sounds awesome, sign me up!
Hate to break it to you but a lot of things you can technically do in the game are not canon.
I was actually expecting to find a good theory or something. Just because we can kill faction leaders means nothing
Wow <3 Korra<3 Giants<3
Maybe... the orc in orgrimmar claming to be Garrosh is actually an imposter and the real Garrosh is emprisoned in the cavernous depths of Blackrock Mountain!
WE MUST SAVE OUR WARCHIEF