ARFOR,
That's the point, speed limits in A/C (have a think about the new D, maybe another legislative change coming up) can clearly be waived, but it is a statutory limit in E and G.
Therefor, only the pilot in command can, on legitimate safety grounds, can determine that 250 kt below 10,000 can be exceeded.
Unfortunately, our regulations are far from clear, as to the authority of the PIC is concerned, compared to FAR 91.3.
See also Part 91.117(d), whereas in AU, the power of the PIC to do as in (d) must be inferred.
Receiving a bluie (administrative fine) in the mail effectively (if not strictly legally) leaves you "guilty" unless you can prove your innocence, including by virtue of exercising the authority of the PIC.
Tootle pip!!
PS: Extract from FARs.
§ 91.117 Aircraft speed.
(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).
(b) Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). This paragraph (b) does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section.
(c) No person may operate an aircraft in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area, at an indicated airspeed of more than 200 knots (230 mph).
(d) If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed.