So he could communicate in some way... but still, once he's dead he is probably less useful than a normal cop, since he won't be able to partake in discussion to such a full degree...
Well, that's my thoughts. I'm not willing to pass up on a chance to kill an anti town player for this, but that's just me.
Also, if CVsoul is still alive tomorrow, then he's presumably going to have been stopped from becoming a ghost or whatever it is he says he'll be, since he claims that that'll happen tonight. In that case, I posit that the mafia would not want to kill him, since he'll essentially be a vanilla townie. So chances are that if we keep him alive, he'll become as much use as a vanilla townie, so he's still able to participate in discussions, and probably won't get killed.
That's my theory.