Well the priest isn't really a power role is it? I mean it's really kind of a diminished townie, so it could work if Laddy thought the mafia already had enough power.

If this is true, it could also mean that there were already 4 mafia in the game, even before the new guys came in, which sounds imbalanced but if the town had enough crazy powerful roles, it could work.

Might even be why Laddy brought in the new guys.