ESPN WORLD OPEN CHAMPION
The analogy is to stress that the eyes work together when the body is perfectly aligned with shoulders level. This reminds me of that the legendary golfer said when ask about "dominant eyes" (they called them Master Eyes) - Bobby simply said he doesn't know if he uses one eye more than the other, he does know that he plays better with two than he does with one.As with most descriptions, the wording is mapping terminology and not exactly the actual thing.
A pistol fired from the hip often fails to align the vision center to the barrel and upright stances, have that sense of the gunslinger.
The instructors using the sniper analogy are moving the player towards the head and shaft alignment.
The extreme interpretation of that is one eye down at cue level.
An analogy is still a mapping tool.
The key is to take the upper body structure into the aiming position consistently.
Footwork is just part of the start of that process.
Pulling that process back into consciousness at some time during setup assures the expert he can move from ready to aim and finally the fire stage.
The game is the teacher