In my view, the discussion within this thread has been nothing but respectful to the poor soul who lost his life and very beneficial to all of us, plus I'm sure those who read this thread but not participate. This is no different to discussions that take place within other aircraft type forums following a sad loss, whatever the circumstance.
@MyNameIsNobody and @kortopates correctly advise to let go of the yoke in this situation. However, this can be quite difficult as it is a natural tendency following the initial shock to grab onto the first object we can due to the shock itself and to stop the sudden backward force. That object is the yoke as we are already holding it which can result in a tighter grip. Where this discussion comes into merit is important advice and reminder to resist this temptation and release the grip.
It is something I have not considered until reading this thread, even though it happened to me twice many years ago in a Piper Aerostar after takeoff where I retained my grip of the yoke as both times the seat did not slide completely back and luckily not enough to cause controllability issues. The suddenness was extremely frightening and something I'll never forget.
This discussion is so beneficial it could have been a thread relating to our seat rails on its own. It is just sad it relates to the loss of one of our own.