It's been forever since I read "Chickenhawk", but I was a 55 IP at Wolters. Much of what Mason wrote about is unique to his experience.
My guess is that Winnie is on the right track-grossly out of trim autorotations could be the basis of the books' highly dramatised events. If my my memory serves me correctly, one demonstration in my training as an instructor went-
Power chop
NO (repeat NO, as in "none") trim correction
Aircraft yaws left and pitches down dramatically
Instructor adds a little more left pedal to complete demo
Pitch down increases to what seems vertical incidence
Cyclic -ineffective-
The planet starts getting big, real fast
Right pedal until aircraft in trim, and control returns.
If you're flying low level and/or never make the connection to correct the yaw with right pedal...