Does anyone know if the harnesses were attached to the mount points inside the helicopter using spring clip carabiners? IMO that would have been the 'go to' point to release themselves from the helicopter, if the harness didn't have a quick release clip on the body.

Carabiner attachments inside the cabin would hopefully also made it easier for passengers and crew to release each other's harnesses if someone was incapacitated or panicking?

Note: I've watched offshore rig crew friends of mine going through 'ditching' training in the pool simulator, and can attest that keeping calm and methodical under the circumstances can be extremely difficult, even under controlled conditions.