The first is that Satan does the inverse of what is True. For example if you desire chastity, he will tempt you with lust. If you desire calm and peace, he will tempt you with wrath and anxiety. Satan tries to be the exact inverse of God! In the actual rubrics for Black Mass (A satanic ritual and direct inverse of the True Mass), you are to face the West. If Satan does the inverse of Truth, then the East must be faced, not only to honor God, but to counter Satan.
My second argument is a battle. When your general is on the front lines of a medieval battle, per se, and is about to lead his troops into battle, he turns around to give some words of encouragement and then charges with them. Is he causing a disconnect with his soldiers as he leads them into battle with his back to them? Is he abandoning them? No! He is leading the charge and rallying the troops! No rational person would say he is turning his back on his soldiers.
In the ancient Mass the priest was to turn to the assembly five times, in honor of and in commemoration of the five appearances of Jesus after the Resurrection. Also the priest is to turn to his right, and then back to altar to his left. Twice, the Roman Missal instructs the priest to turn completely back to the altar to his right, signifying that Heaven is open and that we are in the presence of the Divine.
The priest is the general, who is “in persona Christi” and leads his troops, the lay faithful, into spiritual battle. Even the general, the priest, faces the Commander of the Heavenly Host, Christ, who stands in the East. Christ is the Eucharist and the priest faces Him along with the people, rather than creating a disconnect where he is looking at them rather than everyone looking at Christ. Throughout the Latin Mass, the priest continues to turn around to the faithful with words of encouragement and strength, such as “Dominus Vobiscum” or “Orate Fratres”, much like the general does to rally his troops. By facing the people, “versus populum”, the priest not only turns His back on Christ in the East, but he also is like a general who runs backwards. One of the first revisions Martin Luther and Archbishop Cranmer of the Protestant Reformation did was to remove the Sacrifice of the Mass in order to take down the Church. Their goal was to make liturgy a communal meal rather than a Sacrifice, which is clearly shown in the "Book of common Prayer" produced by Cranmer. The Altar was replaced by a mere table and the priest faced the people.