NSW Police to Be Given Powers to Access and Download Phone Content on the Beat
(www.sydneycriminallawyers.com.au)
The argument is the DEAO is basically a warrant anyway, it needs to be signed off on by the same authorised officers (magistrates, registrars, etc).
All a warrant does is grant the legal authority to go looking for the device. If a cop sees you filming a murder on your phone and arrests you they can already seize your device without a warrant. So a warrant wouldn't grant any more authority than the cop already has at that time.