Because saying one of the party leaders is scum is just too easy. I imagine almost everyone submitted their name to be a party leader and with the leaders being randomized, it feels like it's probably too easy to say there is a wolf among them, for better or for worse. If we assume everyone wanted to be leader, randomizing the leaders means that yeah, there probably is a wolf in there statsitcally. But if not everyone did submit their names, it's still a crap shoot on alignment among leaders which makes it easy for you to say that because we have no idea. Overall, seems super opportunistic.