Last time I flew on QF the Cabin Crew were directed to "be seated" every time the seat belt sign was turned on. Is it QF SOP for everyone in the cabin to strap-in when the sign is on, or just that Captains preference?
If it is SOP to do that, then injuries to the CC would imply that the sign might not have been turned on in this incident.
The self-loading-cargo should still have had them "loosely fastened" though...