The correct play for the SK is to no-kill with a very high probability (say 99%), and kill a townie the rest of the time. (And make this plan known to the other players.) That way, the Mafia can't dare to shoot the SK, because they'd be risking an instant loss if they did. Eventually, they'll hit that 1% chance, and kill a townie, and the Mafia will no-kill or whiff on a doctor in the process; they can't possibly know when the chance is going to be hit. (Use a 10% or even 20% chance if you want to speed the process up, but this raises the risk of the Mafia trying to get lucky, which is bad for you no matter whether they time it right or not.) In other words, the game will go to 1:1:1. (Also of note: you could simply lynch a townie to speed the process up; no player would have any objections to that, as the Mafia and town can't do anything about that, and the SK doesn't want to do anything about it.) So we'll end up in 1:1:1 for sure.
I believe 1:1:1 to be usually a town win but not always; it depends strongly on when the individual players can get online. (I've changed my mind somewhat from my previous writeup of the strategy, due to noticing extra strategies for both town and scum.) I'll go write up my thoughts on it in MD some time.