Jandakot along with its interstate cousins are exempted from the ASIC display requirements due to not having RPT services. I believe a certain portion of Morrabbin does have an area where ASICs are required due to RPT services. The only reason they were designated Security Controlled in the first place was to make funding available to upgrade their airside security boundaries. There doesn't appear to be any mention of it within the Act or Regs so I guess the exemption is issued specifically to each airport with an expiry period. Makes sense as it allows the exemption to be removed without legislative change.
More information available
here
Feather #3 is correct in that you need either ASIC or AVID under CASA regs to fly. Given that the AVID is useless when trying to access any security controlled airport, the ASIC makes more sense.
Pontious, glad to hear your story and lets hope that just maybe, CLARC at CASA have finlly got their s*&t in one sock. They do have a woeful history though so I won't be popping champagne corks just yet.