Because in regular games, scum are usually the ones who do lots of visiting, especially on townies. By comparison, it's more unlikely that four townies visit the same scum player over the course of two nights. The experience I'm talking from here though comes from games which are sized about 14-18 players, so that amount of visits probably means a lot less here than it usually would, especially with that many different factions about. If anything it moves the needle just a tiny bit into the towny area for him, it's nowhere near enough to clear him outright.