Seems like it came from the report linked in another thread today on a C172M crash at Agnes Waters:
CASA has stated that it will not be mandating the fitment of upper torso restraints, even for air transport flights in small aircraft. Given that a significant number of small aircraft in Australia still do not have upper torso restraints in non-front row seats, the ATSB has issued a safety recommendation to CASA. The ATSB recommends that CASA consider mandating the fitment of upper torso restraints for all seats in small aircraft, particularly those used for air transport operations and/or aircraft where the manufacturer has issued a mandatory service bulletin to fit upper torso restraints for all seats. While this is being considered by CASA, the ATSB has issued a safety advisory notice to encourage all owners and operators of small aircraft to fit upper torso restraints for all passenger seats to minimise injury risk. CASA has also advised that air transport operators of small aeroplanes will be required to brief passengers about when and how to adopt a brace position. Finally, the ATSB has issued a safety recommendation to CASA to improve its procedures and guidance for scoping surveillance events.