[Daryl]

From impact, does the body(center of the chest) pivot with the left arm to follow through?

Follow-through is "Both Arms Straight". If Impact occurs while the Right Arm is Bent but straightening, then how could the Left Arm move precisely with the Chest?

Remember that at Follow-through, both Arms are straight, which locates the Hands in the center of the chest. The Left Arm won't become 90 degrees to the Chest until about the Finish Swivel. The Left Elbow needs to bend to allow the Hands to pass "Center of the Chest" Both Arms Straight.