Well, I can't find anything that explicitly refutes this, but it would be pretty odd for everyone else to lose because we managed to prevent Night Kills. It's not like that would directly impede everyone else, unless everyone else is part of a scum faction. Which seems a bit unlikely given the lack of Night Kills thus far.
If there is a scum faction, and not just factions, the non-scum will only win when the threat has been eliminated, isn't it? No NK for a few nights still means that the scum is there, so the town can't win. That means that the scum has to be eliminated, for anyone other than the Watch to win. In that I agree with beet.
So I come back to this, Praz: what is your alignment? Your arguments don't hold up unless you're part of the Watch (which is a direct lie from your earlier statement) or your victory conditions are EXACTLY the same as those of the Watch. And that, I find hard to believe.