From CASR here:
https://www.legislation.gov.au/Details/F2020C00935 with underlining added by me:
Subpart 11.J—Manuals of Standards—procedures
11.265 Purpose of Subpart
This Subpart sets out the procedures for consultation before CASA issues a Manual of Standards.
Note: Manuals of Standards are documents which support these Regulations by providing detailed technical material, such as technical specifications or standards. Manuals of Standards are legislative instruments and are subject to registration and disallowance under the Legislation Act 2003.
The Parliament can disallow MOSs (along with regulations and most of the other regulatory confetti produced by CASA).