Would a simulated engine failure and subsequent auto-rotate landing dangerously unload the head?
Only if you have a FW pilot flying it since the natural reaction is to push the nose down to maintain speed - if that is done harshly as the collective is being lowered smartly, you can very quickly generate a low g situation.
FDR
I made comment before reading the latest version of SN-32; RHC makes appropriate note on the potential for motion of the pilots arm, and that is a factor worthy of awareness.
Agreed, that T handle arrangement isn't conducive to being able to 'damp' your arm using thigh or body contact. If it was LHS flying it as a demonstration on a training sortie with the RHS holding his side of the cyclic normally, the LHS pilot would have his arm up in the air - unless he was holding it 'centre-stick style' - with obvious possibility for PIO.