How would the precedent be set as that? If it's only happened once, and not the other millions of times, I don't think that's the precedent.
I don't even remember Lori having her whole body eaten. I'd have to watch it again. Were they specific about that happening, or did you just assume?
They talked about it on The Talking Dead. In the show Rick finds one walker trapped in the room where she gave birth. The walker is grossly engorged and bones are sticking our of its throat. Lori's body is completely gone except for some blood and bodily fluid smear. Rick kills said walker.
Also:
Precedent:
2.any act, decision, or case that serves as a guide or justification for subsequent situations
https://dictionary.reference.com/browse/precedent?s=t
