The clue isn't that great, to be honest, it's just that there's nothing better.
Here, Heroist's behavior is already suspicious – he first made fun of it, then ostentatiously voted against himself, and then started demanding that everything be explained to him and presented on a silver platter. Would a peaceful player act like that? I doubt it. Overall, it's pretty good; I almost started to doubt that we're dealing with a peaceful player and not a Mafia member. :)
But who knows, Olam (the second main suspect of the first day) already has a scheduled meeting with Modkill, Starost, or the Military Commissar, and most of the others are equally absent from the discussion.