for the lead driver... depends, if they've "entered" the intersection.
https://www.drivingtests.co.nz/resources/turning-right-traffic-lights/
as per the quoted rules (I didn't check their source) provided the intended intersection is clear you are able to "enter" the intersection.
Atleast we don't have to deal with doing hook turns with trams like in Melbourne.
This is correct. The offence is "entering" an intersection on a red light, if it's green when you entered (and your path was not blocked by stationary traffic) then you are perfectly entitled to complete the turn even if the light has tuned red.