There was indeed a point system in Korea. Rotation points were earned by both enlisted men and officers. In September of 1951, an officer would need 55 points to be rotated stateside. Since Henry Blake was an officer serving in a frontline unit, (as opposed to rear echelon) he would have earned 4 points a month. It would have taken him 1 year, and 1 month to be rotated home. The goof here may just be the dodgy timeline.