Well I'm sure that they're going to create a context for the zombies in the game. It's almost definitely going to be explained. You're essentially saying that there is no context, despite the fact that the game isn't out until next year and you probably don't have a full idea about what the context of the game is anyway.
That's why I said "as far as we know."
By context, I mean the MGS universe as it stands.
My whole point is that creating a context for there to be zombies in the MGS universe isn't unreasonable or far fetched.
...and there have been 'zombies' that fit the current MGS context: Gray Fox, The Skulls, the puppets and the PTSD troops from MGS4. They fit the MGS universe. Being dragged into another universe to face inter-dimensional space crystal zombies doesn't (at first glance), so I don't think it's unfair for people to be taken aback by their inclusion. Post Silver Age Superman suddenly being able to cast spells doesn't work within the current context of the character, nor does it have precedence, so I wouldn't be surprised if folks went "hang on a moment" with that either.
It's a pretty trite point to make, saying the world has all kinds of crazy shit going on it, therefore ALL crazy shit is suddenly acceptable or will automatically fit the world. It ignores the fact that the crazy/whacky stuff Kojima brought to the show generally ties in with larger thematic elements. It's hard to believe, I know, but there is a certain, far out, often ham-fisted logic to it.
Yes, that includes the Bee Shitter.