I will offer you a reply, that represents my "best" understanding of the shaft bend phenomena.
I am going to presume that the shaft bend is "real" and not a camera artifact.
Let me start with the orbiting ball.
I have modified this diagram by adding dotted yellow/red lines. The red dotted line is in a perfect straight line relationship with the yellow dotted line - which means that there is an instantaneous relationship between cause-and-effect. If the hand (cause) moves in a circular arc, then the orbiting ball (effect) will respond instantaneously and also move in a circular arc (due to centripetal forces). There is no delay in this system when the string is continuously taut, and the system is in a state of balanced motion.
Now consider the golf swing.
I have placed yellow dotted lines and red dotted lines (as previously placed on other images) on your photos.
Starting with image 1
The clubhead sweetspot line (red dotted line) is lagging behind the hand pull line (yellow dotted line). I believe that this is due to clubhead inertia, and this phenomenon is only possible with a flexible shaft.
Image 2
The clubhead sweetspot line is ahead of the hand pull line. I believe that this is due to the fact that the hands are going through the tight radius turn of the small pulley of the endless belt - the time point where the club releases very fast. The fast releasing clubhead manages to get slightly ahead of the hand pull point - only because the shaft is flexible.
Image 3
I believe that the shaft has a double bend. The first bend (seen at the top of the shaft) is due to the same phenomenon as seen in image 2 where the central part of the shaft gets bent forward because the clubhead's speed is fractionally faster than the hand pull - during the pre-impact phase of the downswing. Then impact occurs, which slows the clubhead down. That causes the clubhead to get pushed back secondary to the collision - and that causes the peripheral end of the clubshaft to bend backwards while the central part of the clubshaft is still bent forwards. This snake-like bend phenomenon is only possible because the clubshaft is flexible.
Threaded Mode
