Before anyone gets over-excited and starts telling people to sod off, be aware that the big airports also employ contract security guards to check ASICs and the AFP/AUP will do it occasionally as well, if they get super bored.
Division 6.6 of the Aviation Transport Security Regs refers. It also requires said official to identify themselves.
YPJT, I'm sure there used to be a section in the regs that required any ASIC holder to challenge a person in a designated area if they weren't displaying an ASIC, has it disappeared or am I hallucinating legislation that never existed?