Thanks for the replies.
The double blips. I begged the question some 1,000 posts ago about the possibility of the blips causing alarm because of sudden g forces, despite the graphs not showing any such detail. Strangely, the higher accelerative fluctuations come later - I imagine distressing belt-tugging forces.
The consensus back then dismissed the possibility. So, looking again for why the trim wasn't continued. The extract above is again thought provoking; giving an insight into the psychology. But I'm still not convinced. The g force noise does go up during that period, but not in any recognisable sustained pattern. The column inputs are very well mirrored in g forces shortly after.
05:41:35-40 -ish shows a sustained average positive g despite coming from a series of no doubt powerful tugs. Since it seems to be real, and showing in a definite improved pitch attitude, one wonders why this could not be sustained.
All in all, I still have great sympathy for the pilots, which is no doubt strongly biased by my short flight with the stick shaker going. My highly competent FO pointed in turn at the six speed and attitude dials, but even then half a lifetime of indoctrination was relentlessly tugging at my mind, and that's with nothing else being wrong.