I talked to the CAA here (LBA) this morning. They confirmed that in principle, the SIDs are mandatory as they are part of the inspection guidelines and both CAMO and individual maintenance programs are based on the manufacturer's maintenance guidelines.
EASA and the CAAs will look into the SIDs and decide what to do. These inspections are much worse than they appear at first look. If this becomes mandatory, it might be worth going to FAA-reg.