I'm crazy busy today, so I won't be around much, but will try to keep up.
I don't know if I'm supposed to be flattered you'd think I'd lie about masons, but I'm not. If you believe I'd do it, you are insulting me pretty badly. You seem to forget who invented the setup we are playing.
But let me break down what you aren't considering, and what I know because I designed.
If scum fakeclaim a role that requires more letters in a setup than actually exist, their chances of being caught increase more than you are accounting for.
Take your specific example, that the masons are lying.
This game is DMMMBT. That's a Doctor, 2 Masons, Roleblocker, UB vs. Strongman, Godfather, Goon or Strongman, Godfather, 1-Shot BP.
Now, take out the masons. We don't add letters, specifically, because there are no other PRs. We have:
DBTTTT or EEEBTT. That gives you a scumteam of 1-Shot Strongman, Godfather for the first one and Strongman, Godfather in the second. You need to use that information to decide if a scumteam is willing to fakeclaim masons.
DBTTTT -- scum knows it is 3T or 4T, but do not know if masons, UB, IC exist. Remember that scum can only add MMM to a setup, because they can't account for the UB existing or not and it will flip or claim eventually. So, if they are adding MMM, they are changing the # of Ts, which means if the wrong scum flips the entire team is caught.
EEEBTT -- scum knows it is 1T or 2T, but do not know if masons, UB, IC exist. To decide to try to add MMM to a setup that doesn't have enough free letters is stoopid dumb. They don't know it's EEE, but they can't just assume it. Anyone single other PR claimed and the setup was screwed up.
That's the way you should be breaking this down. Not your hypotheticals so far. Take what we know, apply it to the situation. I don't know why anyone is wasting their time doing this -- we need to find the two town in 5 players and lynch correctly 3 times in a row.