Your arguments had me vexed Thorin, and I had never thought of Samuel as being a demon. So being extremely curious I took the time to look through papers, essays, and other things relating to the subject. The essay I found, that I think sums up what most scholars are saying about the subject comes from a Bible difficulties dictionary in the Zondervan dictionary. It reads:
What took place in 1 Samuel 28:8-16? Did Samuel really appear to Saul? Did Saul actually talk with him in the witch’s cave?
There is little doubt that satanic powers are able to produce illusionary images and communicate with the living by this means. Such “lying wonders” (2 Thess. 2:9) are part of the Devil’s stock in trade. On the other hand, it certainly lies within God’s power as well to present an appearance for the purpose of conveying His message by a special revelation.
The oracle delivered by this shade or apparition sounded like an authentic message from God, with its announcement of doom on the guilty, unfaithful king. It even sounded like something Samuel himself would have said, had he remained alive after the massacre of Ahimelech and the priests of Nob (1 Sam. 22:11-19). Therefore it is entirely possible that this apparition was the actual shade of Samuel himself, when he asked, “Why has thou disquieted me, to bring me up?” Apparently Samuel had been directed by God to leave his abode in Sheol or Hades (where even the saved believers awaited the future resurrection of Christ, which would bring about their transferal to heaven itself) in order to deliver this final message to King Saul. Conceivably the deceased Samuel could have communicated long distance through an apparition in the cave of Endor, but the words “to bring me up” make this very doubtful.
On the other hand, it should be observed that the witch herself was quite startled by this ghostly visitor, as she said, “I see a god [Heb. ‘elohim] coming up out of the earth” (v.13). This clearly implies that this authentic appearance of the dead (if such it was) was no result of her own witchcraft; rather, it was an act of God Himself that terrified her and that she had in no sense brought about in her own power. It would seem that God chose this particular occasion and setting to give His final word to the evil king who had once served His cause with courage and zeal. No scriptural basis for spiritism is furnished by this episode, nor for necromancy—both of which are sternly condemned as abominations before the Lord (Deut. 18:9-12; cf. Exod. 22:18; Lev. 19:26,31; 20:6,27; Jer. 27:9-10).(Archer)