I didn't see that game, but it wiuld be very silly indeed not to lynch the masons at lylo in that case, and it would take ridiculously strong incorrect reads to override that. If the town did have that, good job scum, but my guess is that they just messed up.
scott_pilgrim, the thing is that there isn't a 97% chance of them being scum, even independent of reads. There's significant WIFOM and other complications involved. 97% of the time the role doesn't exist. Say 47/97 of those times, scum fakeclaims, and town always claim. Now there's a 47/50 chance they are lying, given they claimed, which is 94%. That 47 number came from nowhere though; it's usually lower, and hard to estimate. That's why the 97% figure is very misleading and usually entirely irrellevant to the game.
It's still very scummy to claim a role unlikely to be in the game, and in the case of masons, should usually be lynched in lylo because of it.