As clearly indicated in the second last bullet point under DGR 22.214.171.124, a DGD is basically not required for UN 2807 Magnetized material (refer PI 953).
Referring to PI 953, at the start it says: "Magnetized material with field strengths causing a compass deflection of more than 2 degrees at a distance of 2.1 m but not more than 2 degrees at a distance of 4.6 m are not subject to any other requirements in these Regulations when carried as cargo, thus eliminating the need of a DGD.
Exceptions to the foregoing are shown as (a), (b), (c) and (d).
(a) requires prior arrangements between the shipper and the operator. A shipper's declaration is explicitly not required provided the words "magnetized material" and package count are entered on the AWB.
(b), (c) and (d) refers to "handling label", "package stowage" and "incident reporting" respectively with no reference to the need for a declaration.
The final paragraph states if the field strength causes a compass deflection of more than 2 degrees at a distance of 4.6 m, it may only be transported with the prior approval of the State of Origin and the State of the Operator. Such special approval may indicate the need of a DGD however since a DGD is basically not required the chances of such requirement is considered remote.