kkong
I am not sure why some posters believe that pilots should be exempt from an investigation into possible criminal negligence?
No-one has suggested they should be.
If the pilot(s) are not found to be criminally negligent (based on CVFDR analysis by the CAA), no charges will be brought and no information from the CVFDR will be disclosed.
Have you considered whether aviation safety is better served by investigations in which all those involved are free to speak openly without fear of being prosecuted or by criminal investigations in which anything they say may be used as evidence (against them) in criminal proceedings and in which they have the right not to answer questions?
Although this particular case related to a helicopter accident, the same issues apply to all aircraft equipped with CVR and/or FDR.