From the rules:
Random events-On two occasions that will be randomly selected before game start, random events will happen.
one time a soul will be switched, if it is an innocents soul they will work with the troubled souls. If it is a Ghost hunter they will work with the troubled souls, they will be communicating with both sides and can not reveal to either side that they are..although their goal is to work with the troubled souls and take out the ghost hunters, they can not name them to the troubled souls, they also can not reveal to the ghost hunters they have been turned or give the names of the troubled souls to the ghost hunters. If a Troubled soul is selected they work for the ghost hunters and the same rules apply to them. If the Dr. is selected they will work for the troubled souls they can reveal to them that they are the Dr and they still have the power to protect and use the vial.
So by order of events if the scum turned someone they would now be a troubled soul, the random event should then mean the troubled soul would work with the GH's but they could still communicate with the TS's and the TS's would not know about the switch. If this was the Random Event it doesn't follow those mechanics.