It kind of does... for now. But keep in mind that we haven't actually seen Arthas yet (and technically, we don't even know this is him -- it might just be, you know, a mistake in shipping or somethitng like that). Clearly, the Argent Dawn can handle this little "event," and none of us need to worry.
Sure. Just keep thinking that. Meanwhile, more zombies have started appearing all over the world. Mind if I chew on your skull for a bit?