I would link the thread but I forgot the title, it had a good amount of posts though (Could have got closed though)
I think TSD posted a lot in that thread though saying that normally the weapons in the DLC's for Treyarch have been Zombie only, and that the CoD Engine currently could not support a new DLC weapon.
I think it could if it was a locked on disc content, which I think it is, but at the same time it does make sense for being only in zombies, the name "Peacekeeper" and zombies goes quiet well.
I wouldn't mind it it it was in MP, and also if it was only for Zombies...I think we'll have word soon but someone else pointed out that they might not even confirm if the weapon is Zombies only because of fear for loss of sell (Which makes sense also.)
@haha, yes, i've seen 100k+ players on it during late nights, and even when it's early morning (3-8AM) at least 25-75k players are on, no lie. Not sure of PS3 numbers though.
Besides, zombies spices up Black Ops 2 more, it'd be more dull IMO without it.
*Cough* MW3 with spec ops. *Cough*