Does it need to be flipless? While I do agree on the fact that it should be a Neutral role, I feel like it should be altered or denied entirely rather than modifying the setup to be flipless.
> Altered Town needs to ensure “threats to Town are not eliminated and no Town are alive”.
> Altered Mafia needs to ensure “at least one Town is alive, or prevent Mafia-Town parity”.
FMPOV, the root of the issue is rather how you want to deal with these “altered factions”. Flipless wouldn’t solve the constant doubt of “which players’ win conditions have been altered?”
If you were to consider “prioritize the players’ fun”, then I don’t think many people on this site would appreciate having their win condition changed mid-game.
Any Town and Mafia would have to suddenly reverse their reads and somehow convince the rest “this change makes sense”. I don’t think that’s going to be fun for the players.