Well, I'm no clearer now that I was! There are too many inexplicable events to make sense of this, including pilot input and THS angle. It is unfortunate we do not have the RHS IAS readings, and I'm not clear from that report which seat PF was in, nor which IAS readings he was reacting to. A 'zoom' from FL 350 to 375 with 7000fpm is pretty dramatic. It also appears that they were close to being unstalled at the 375 point.
The only observation I can make is that I have seen a full and maintained nose-up demand from a pilot in a different aircraft before, in reaction to a large (and unexpected) rate of descent while stalled.
Way to go yet.