What if you thought about things along these lines?
If you keep the connection , the hanky tucked under the left arm pit, then the Hands will be moving at the same RPM as the Pivot. Only. But if you let the Pivot provide the initial turning power and then the Left Arm in turn accelerated away from the Pivot , "blast off" would not the Hands be all the faster for it?
There's more to that sequence of events in the golf swing but given that logic where should the hanky be when a golfer is at Follow Through, both arms straight? I'd say on the ground. Loading the #4 and hard is a good thing but you have to let it open up or fire.
I realize this is a contentious topic but thats the basic logic I apply to it.
I agree about the hanky dropping. It has to drop if you complete the motion. The question is perhaps: When should the hanky drop? I think it should drop later (with regards to where the ball is) the more shallow shaft angle you have at impact. Thus earlier for TSP-ers than for EP-ers.
What if impact was at exactly the same location for elbow plane and turned shoulder plane singers? Would the handkerchief then fall at the same location after impact?
I am not a TSP expert but I have to let the Left Arm fly earlier when I TSP than when I EP. I think the flatter inclined plane you use through impact the longer you can keep some of your PP#4 pressure. So I believe that an EP-er would typically drop the hankerchief later than a TSP-er. But you should know better than me how this works from the TSP side of things.
Connection maybe a better term for minor stroke involving the left armpit with zero pivot.
With your Pivot , Zone One, Zeroed in a Minor Basic Stroke , would not the use of a Hanky also zero Zone Two, the Arms? Leaving you with only the Hands , Zone Three to move the club? The Peck Minor Basic Stroke 10-3-F or similar.