109 prop pitch (rpm) and the supercharger

[Crumpp]

that is non standard pitch management at high altitudes as described by a LW pilot who has actually been there

He does not say or do anything "non-standard". He just explains the right way to manage the pitch on the propeller is to constantly change it.

That is why you hear the pulsing of the pitch change. You hear that at any governor check on run up of a CSP equipped aircraft.