The cyborg said that as a bluff to scare the townsfolk to turn the guy over. The ruse would not have worked until the cyborg entered the town. The cyborg was sieging the town to compel them to deliver the guy to him. The cyborg did not want to kill anyone other than his target, but the sheriff was protecting the target. The line encompassing the town was a plan to achieve his goal: kill the target and no one else.