With respect to the apparent reduction in pitch rate observed on the videos of the accident manoeuvre there are a few point to consider.
When a looping manoeuvre is viewed head on, or when there is a significant planform aspect, the observer's perception of pitch rate is based on the rate of change of apparent fuselage length (nose-to-tail length measured tangential to the sightline). The relationship of this length and absolute fuselage length is a function of sine(pitch attitude). Therefore, for a constant actual pitch rate the perceived pitch rate will reduce passing a pitch attitude of 90 degrees (up or down). This is why this apparent phenomenon occurs on many of the videos.
In the report there is a plot of pitch attitude vs time to impact (Figure 13) commencing at 90 deg nose down. A straight line can be drawn through the error bars from 90 to 0 deg, indicating a constant pitch rate. Even if the data points are joined a significant pitch rate exists at 90 deg nose down. Therefore, if a reduction in pitch rate did occur it would have to have been significantly before the down vertical line in order for the pitch acceleration phase back to a significant, steady state pitch rate to be completed by the down vertical.
The aircraft had achieved a level pitch attitude before impact with a rate of decent at impact which was survivable by the pilot. The height loss data presented in Appendix H indicates that a maximum instantaneous pitch rate pull through was required in order to achieve the radius of the accident manoeuvre. Therefore, if there had been any reduction in pitch rate from this during the downward half of the manoeuvre then a higher rate of descent impact with a nose down pitch attitude would have occurred.
Based on the above, there appears to be no evidence to support a postulation of a reduction in pitch rate during the downward half of the manoeuvre.