During the quest, the player joins MacCreary to kill Winlock, Barnes and the Gunners in the Mass Pike Interchange. All the gunners in the area are hostile as soon as they see you, except Winlock and Barnes, the very same quest targets. They will become hostile only after being attacked directly. It's possible to kill every gunner in the area, but these two will remain neutral, and killing them count as murder in the pip boy stats.