Gummy's only being allowed in so long as she doesn't reveal who the other mason is. And, seeing as I know how trustworthy she is, I see absolutely no problem with letting her in. So she knows the role of one player, what's the big deal?
The
big deal is she is aware of a confirmed townie. Whether she reveals the role or not, it is still a hindrance. Suppose player X is the mason. A bandwagon is starting on player X. LittleGumball would have usually voted for Player X, but doesn't because she knows Player X is the mason. Player Y is lynched instead. Or, LittleGumball could unintentionally reveal who the mason is. Bandwagon in Player X. LittleGumball speaks against it, citing that Player X "acts very town-like". Obviously LittleGumball thinks so, because you are biased when people are confirmed town. We all take this to mean "Player X is the mason", based on LittleGumball's unintentional reaction. Player Y is lynched instead.
The big deal is that
no player should have an unfair advantage
no matter how small. Sorry, but perhaps we could find another replacement.
EBWODP
Any sort of advantage could have adverse effects on the game, effects which I don't want to deal with. I don't want to win as a townie if my squad is unbalanced.
Also, a vote does not work because everyone has different roles and different factions have different numbers of people(townie vs mafia vs 3rd party, etc). Majority is an unfair way to decide something that could negatively affect the game.