I'm pretty sure it's because some of the scenes explicitly have her die. So I think it's a covering their bases sort of thing.Why the Necro Tag? Did I miss it or am I just desensitized?
While some people won't consider it explicitly necrophilia, because it's not corpse fucking, there are a fair number of people who don't like necrophilia that would also be put off by the character explicitly dying in a scene without the warning that things could reach that level.
It might also just be a carry over tag from the first game that had zombies be one of the enemies that could rape you, as well as scenes where she died.