This isn't an aiming system in the classical sense, where you're trying to find overlap, a ghost ball, or a fixed contact point. He's not calculating anything. He's building a clear picture of the shot before going down.
The left-right head movement cleans up perception. It gives the brain more depth information and removes doubt.
The sequence also matters. First he locks in the object ball-to-pocket line. Then he checks the cue ball-to-object ball line. After that, he commits without adjustments. He told me that since his fundamentals are well developed, trusting and executing his perception works very often.
So the purpose of this routine isn't to aim better in a technical sense. It's to remove uncertainty before the shot so you don't start steering or adjusting during the stroke.
