The spiritual presence of Jesus was so obvious the demons reacted to him from a great distance! A crazy, violent man with invisible demons recognized a Galilean traveler who was invisibly the Son of God. His spiritual power and presence could not be ignored.
The drama of the drowning pigs gets most of the attention, but the commission of this newly freed man is a great commission for every believer, "Go to your home, to your people, and tell them what the Lord has done for you and of his mercy." That mission was more important than traveling with Jesus!
The pig farmers reject Jesus out of fear. Jesus will mess with your business!