There is presently no evidence that your hypothetical situation is correct, let alone that any scum would have been informed of it. However, there is very good reason why scum would want people to look for serial killers or multiple scum factions: it sets people to look for different cues than one looks for in a normal mafia. When looking for Mafia, we search for signs of collusion. But serial killers are entirely independent, with no loyalties to anyone. And multiple faction Mafia end up drawing "teams", which also reflects differently in their behaviour.

Essentially, it would serve to distract players from searching for the actual mafia. If you'll recall, it was likewise Isaac's unfounded Serial Killer hunt that first drew my suspicion in the Marvel Superheroes mafia game.