Yr er er er er right or wrong,
CAAP42B-1(1)6.1 does not answer the question of whether/weather/wether (just to give yr a few choices) an OEM SERVICE BULLETIN is mandatory, ie: a maintenance manual instruction, or advisory.
Nobody here has yet come up with a AU REGULATION that makes an SB mandatory.
If you literally take OEM SBs as mandatory, there could be no engines (or most other components) on condition. The bulk of the aviation world (airlines) work their aircraft largely "on condition".
In the airline world (or, if you like, large Class A aircraft) SBs are at the discretion of the registered operator, unless the SB has been made an AD.
Tootle pip!!
PS: With a couple of additions, Schedule 5 is a copy of FAR 43, Appendix D and is (sort of --- see the additions) works the same way -- it is not really a "system of maintenance", it is an inspection schedule for an annual inspection, where applicable the MM for the type is the prime reference for carrying out the work that constitutes an inspection.