I think Blizzard’s hang-up is that they won’t kill a character that looks reasonably like an actual woman, because of what people would say to them on twitter about it.
So Vyranoth, who walks around like Cindy Crawford caught in a snowstorm, HAS to switch sides and not be killed off. While Raszagath is fair game for killing, in Blizzard’s eyes, because she’s just a slavering monster - notice that Raz never has a visage.