Their argument makes sense, which is that at least as far as the composite is concerned, are those scars or just furrowed brow lines drawn by the police artist? That picture (to the best of my knowledge) is based on (a) a couple of kids who looked out of a 2nd floor window across the street from the taxi where Zodiac wiped the door handles, reached into the cab to grab a piece of shirt, and walked away (in the evening), and (b) two police officers who drove past a man walking away from the scene and later realized it was almost certainly Zodiac. Neither seems like they got a close enough look to accurately describe lines on his forehead.