Can game balance be used as a means of catching scum?

[shelper]

Myself and a couple of other players had an interesting AIM game yesterday night. There were 2 night kills night 1 one of the victims being scum, two docs outed themselves that day and protected eachother the next night, and no kills happened night 2.
I was one of the docs, and figured that a scum could claim doc, and choose not to kill to appear as a doctor, but that would make the setup 2 scum, 1 SK, 1 doc and three townies.
The other doc believed my claim saying "you have to be who you say you are, otherwise the game isn't balanced".

Personally, i don't think you can rely on game balance that heavily. Now that i look back on it, he was probably right in this case, but in larger games, or playing with mods that have a tendency to think of insane setups, i don't think it can be relied upon like that.

Your thoughts?