PP1 can also be Extensor Action or ACC1 driving on the thumb. but for me , this PP could be not at the thumb but above the thumb muscle close to the trapezium.. with the heel of the right hand( carpitate) acting on the "thumb"
If the pressure point 1 is that low, both hand may have to be detached. and not working as one unit.
PP3 is more of a sweet spot of the club head, to allow tracing the sweetspot plane..hope i got the right expression here... its location should change depending if using sequential or overlap release...
PP 2 .. is actually a Uncocking pressure.. working with PP 4.. the PP4 will help to allow PP2 to uncock for swinging... so kinda a Passive thing.
Just the way I know it.

of course Mike is the expert here .