javier vasquez – Toad's Cave

I’m kinda confused, Warren stabbed Vasquez in the stomach then sliced off his head at the neck, why didn’t his head turn Z?
Cause his brain would’ve been intact, he should’ve turned into one of the living heads like at the Z weed place, shouldn’t it? maybe I missed something

When Vasquez returns I’m gonna be really disappointed if Warren doesn’t kick his ass or slap him upside the head for disappearing