I’m being a bit of a bush lawyer here...
The distinction I see is that while a planned flight may be classed as either VFR or IFR, by definition the only time it is “operating under Instrument Flight Rules” is from takeoff to landing.
It is axiomatic that the taxi phase of flight, up till now at least, is a visual procedure that does not rely on instruments for navigation.
The wording of the PED rules seem to support this interpretation as they refer to preventing flight deviations due to electromagnetic interference. This is not applicable to taxiing. If it were surely the same rules would be applied to VFR flights taxiing.
Of course none of the above prevents airlines from making a more restrictive rule for practicality. But that is covered by the Aviation Act not CARs.
A bit pedantic and I’m not really a lawyer but hey...they are supposed to know this stuff and so is the minister.
NZ CAR 91.7
AC 91.5
Av Act 65J