Surely the LAME's only responsibility is to perform the work requested of them (by the person responsible for the continued airworthiness of the aircraft)
Surely you jest. Or misunderstand the intent of the CASA requirements for continuing airworthiness.
I would also be interested in talking to the AWI who told you that only part of SB643 was applicable to your aircraft. PM me his details if it wasn't in confidence, as this is a direct contradiction to both western aust and far north QLD interpretation