That is a huge space for a instance! Ahn’Qiraj shows up when you select it. So why not this then? Zul’Farrak would have its own fiefdom too if that was the case, but you see it in Tanaris. Scholomance is the same, it does not have its own borders either.
I am not saying you are incorrect and that might be the answer gave, but it sounds incredibly lame.