Steve, I agree with you that the "clutching the throat" after the ~z222 strike is probably not the whole story (and may not even be the main part of the story).
Two things have bothered me around the grasping for the throat or choking move as a reaction explanation.
The first is that a major contraction of the deltoids to raise the elbows up so high, for me that seems to actually put the hands a little too high to readily come back down and access the throat/neck, the chin become a blocking agent and would seem to hinder a quick natural throat protection response. Having the elbows down low and with just flexing the forearms up to facilitate grabbing the throat seems more efficient natural emergency response there. That is one reason I don't like the throat grasping explanation.
The second is that I don't recall seeing any other really rigorous medical explanation for those reactions. They are so unusual, I would have expected to find more on what could cause it. I can't recall if I have linked this before, but I went looking in neurological resources and journals for possibly a more detailed explanation. Spastic Paralysis seemed to describe the injury caused by associated nerve trauma, and if the reactions can be quick to engage, JFK's condition on film looks to have most all the typical symptoms seen in the literature.
https://sites.google.com/view/spastic-paralysis/home Sometime maybe I could find a top end neurologist to share this with and get comments on if this, vs. choking, is a more likely response to what we see on film.