Well, for a map like Monsters, It would be impossible to maintain the Wizard. On Das Schloss, Hubschrauber A & B would kill all the Parachutes off instantly, due to having a ton of Troops on them.
Edit** Also, what the original plan was, that every Neutral would attack anything beside it, if it had the forces. Now, with Killer Neutrals, this threw a few maps like the 2 i mentioned out of whack. Now, from your map, all the Neutrals on the streets are killers, correct? Well, with this new feature coming in, it would ACTUALLY make your map nearly impossible to play, since if you have 4 starting points, and only 3 troops to deploy, you'd be kinda hooped. Because the killer neutrals, on the streets, would constantly be gaining 1 each turn, along with Neutrals in the areas off the streets. But with this, the Neutrals won't be gaining 1 each turn, but still remain as if this game type wasn't played.
The only way to ensure that the 'zombies' (neutrals) never went away is to use killer neutrals.
I'm not saying that we will remove killer neutrals off the maps. I'm just saying they won't be considered "infected". This game type would more likely give you a more zombie like feel, as each room is filled with so many infected. There still will be killer neutrals on the streets, they will come back after each time someone conquers the territory, they just won't be able to attack off their own space. Maybe create a safe room for starting terts? So that in case this gets implemented, infected won't be charging into your starting terts.