I'm not sure even now whether you got the point that the kerfuffle regarding the "non-ban" was a self-imposed ban
on US Naval vessels by the US Navy, attributable to the enactment of the New Zealand Nuclear Free Zone, Disarmament, and Arms Control Act 1987
, and the US Navy's reluctance to comply with that Act, coupled with their wish/expectation to have the NZ government make a special exception so that the US Navy did not have to comply with the Act.
The NZ government at the time - and now - could not agree to making any exceptions to the Act it had so cogently put together, so the Act applied equally
to all ships of all types and under all/any nation flags that might want to enter NZ harbours. It was realised that it might make it difficult for some visiting warships from other countries, but it was a rational Act, and, notwithstanding, one would expect that any visiting ship to a country would respect the laws and sovereignty
of that country.
The Act supported NZ's primarily pastoral economy, which has a huge international and government-authorised dairy monopoly (sort of "co-operative") called Fonterra, which is the single biggest company and dairy produce export-earner in the NZ economy, generating on it own more than 7% of GDP. I recall reading somewhere that Fonterra controls approximately 30% of the world supply of dairy milk powder.
The clean, green nuclear-free
slogan is arguably at best a marketing puff to establish/tart up and differentiate a marketing image for all this. Other sectors sharing in benefit from this image would probably include: deer meat (venison) and velvet (young antlers), beef and lamb meat, Kiwifruit (Chinese gooseberries), various shellfish farming, the wine sector, and other pastoral/horticultural produce. I presume GM foods would definitely be a no-no in such a context.
Ironically, some of the greatest environmental damage - including pollution of land/waterways and destruction of natural bush - seems to come from the milk/dairy industry, and all sorts of local bylaws seem to have had to be put in place to limit this damage.
Fonterra's operation is so big that it must be difficult to manage its environmental footprint, wherever it operates in the world.