TGM does not use the term COIL or X FACTOR, yet both terms are commonly used in golf instruction vernacular.
Some swings... VJ Singh, Tom Weiskopf ... appear to coil on the backswing. Some swings... Nicklaus, Snead... appear to have little coil on the backswing. The Nicklaus type coils during the transition, or Start Down, if there is one.
The pictures in TGM... such as the one in 9-2-6, appear to have little backswing coil. I believe this type of position may be easier on the body, especially those with lower back problems. Sam Snead played for a long time!