That's what I think, but goodness who knows in this game. It is almost always assumed that Mafia/witches have factional communication. It'd be very interesting if there was some mechanic affecting this.
As for Scruffy's vote? I think Mr. Carny just assumed Mafia could communicate and worked off of that assumption. It is such a basic rule I didn't even notice it wasn't on Karifean's OP, which doesn't necessarily mean anything in and of itself.
Let's not forget the slim-yet-possible chance that there might be a third party unaligned between Town and Mafia. Roles like Serial Killers and Survivors exist, though they are fairly rare in the EoFF meta.