It's not a controversial stance within NZ these days, nor seen as particularly partisan there. Other countries (especially the US given what it meant for ANZUS) might find it more so.
It was controversial at the time, resulting in the US kicking NZ out of their security alliance (something that was of no detriment to the US), and continues to be controversial every time the topic of a US ship coming to NZ is brought up. The fact that the only outcome this policy has ever achieved is the prevention of allied navy visiting NZ is a very consistent source of controversy in NZ. To claim otherwise is simply rewriting history.