I propose hypothesis 0: Master, Nefeela, Lynx/Gumer/Revan (pick 2).
But seriously, I don't really believe Ment is Mafia. Maybe 30%.
For me, Gumer and whoever else appearing 15 minutes before the day closes on the first day, and with only one or two messages that day, looks like a nudge in the Mafia chat.
I haven't gotten to my table yet, but how someone calculated that Master is 100% Mafia, and why someone else agreed with that – it all seems unclear.
But I haven't thought about whether this is even possible yet; first, I need to at least get to the paper and start thinking...