Actually it speculation at best. Suarfang showed two rogue undead. He also said he tracked them. There a ton of holes in his store. Beside the fact he thrall. You only going to send two rogue. They sure did not fight like super elite fighters. At best regular troops.
At work we loads of fun coming up with why. Being BFA and the way they do things. Good luck. Like the said she going to break and brain wash that guy. Impossible forsaken taken a while before mind settles in. Even then there minds kind of wonky. Just anther weird example.