Because if he hadn't been, the townies would have lost, as per the Mafia to Townie ratio rule.
Edit @ Kaden: Except that I gave reasons, which were to see reactions. I stated right off the bat that they might not be Mafia. But last game, a big thing that tipped me off to Piper being Mafia was the fact that every time she got accused, she would immediately blame her accuser of being Mafia.
Besides, anyone who would seriously look at someone saying "Let's Lynch Kami cuz he's green, lol!" or something along those line, and vote with the person would be highly suspect.
Edit @ Kaden: Except that I gave reasons, which were to see reactions. I stated right off the bat that they might not be Mafia. But last game, a big thing that tipped me off to Piper being Mafia was the fact that every time she got accused, she would immediately blame her accuser of being Mafia.
Besides, anyone who would seriously look at someone saying "Let's Lynch Kami cuz he's green, lol!" or something along those line, and vote with the person would be highly suspect.