It doesn't. It doesn't mean that at all.
Look at Phantasy Star III. Was Dark Force defeated by Orakio and Laya? No, he was trapped. Was Dark Force defeated by Rhys's grandson? No, he was trapped. Dark Force is patient.
He's also capable of possession and shapeshifting. Everyone seems to think that the threat that Algo had faced no longer existed. In other words, they let their guard down. All it would take would be for someone to inadvertently release Dark Force from wherever he may be trapped, possibly underneath the former site of the ancient city of Paseo. He managed to trick Chaz, Lutz, and an effing android, who you would think would be able to detect that Seth wasn't human. He's pretty good at this. All it would take would be for him to take human form and orchestrate a Palpatine-esque coup d'etat in order to rule over Algo with an iron fist and destroy it from within.





