Now knowing the full setup, I have to say that the setup was heavily skewed against town and FOR Insomniac in a very unfair but not entirely obvious manner.
First note that there are 5 scum in a game of 13. This is a HUGE scum population. Now, this could still be balanced with scum trying to snipe each other, but that wasn't going to happen in this case for several reasons.
First, most scum were not aware there was a second scum team and thus were not gunning for them. But second, and most importantly, Insomniac was in BOTH scum teams and was thus in a unique position to steer scum away from each other.
When there are two scum teams, part of the balance MUST come from scum attacking each other. Insomniac heavily mitigated that possibility.
Finally, note that Insomniac was a KNOWN team mate to 4 other players and that he had the opportunity to keep the 2 on one side from going after the 2 on the other side, and vice versa. Even though they were 2 teams, it is not a far cry from a single scum team of 5 which, I hope all would agree, is very unbalanced against town. As it was, there were 4/8 players at the start who would not have wanted to see Insomniac lynched. As the game progresses, there are fewer people who would ever go after Insomniac. I don't see how Ins could have lost, really.
Now, perhaps balance was meant to be achieved in powers. ashersky's Mastermind had high potential for sure, and Galz was pretty good too. Archetype I think was actually strongest, even in his unevolved form. But ultimately, the most potent power is knowledge and influence. With four scum teammates, he had far more knowledge than town could overcome.