That's just a projection through Twisting Nether, propably cast by Illidan. You can't see Azeroth from anywhere else on Outland. Outland isn't even in same plane of existence as Azeroth.
While Azeroth and Argus aren't really anywhere near each other, they currently have gargantuan portal open in their respective skies which makes them visible to eachother. Outland isn't anywhere near them.