It depends on what you would consider a strong stance. The previous National Government sent Te Kaha through the South China Sea escorting a Nimitz-class aircraft carrier battle group after a US Destroyer suffered a collision with a civilian ship and was put out of action (2017). That sounds very assertive compared to our usual position on such issues, and yet it was later revealed by the Defence Minister at the time that they had alerted China to the ship's involvement to avoid unintentional escalation. There were no longstanding repercussions. The NZDF has also long been involved with Five Power Defence Arrangement exercises in the region. The later agreement would offer a good existing platform for engagement with countries in the region with shared concerns. Of course, that assumes that you think such actions are of strategic interest to New Zealand - many in the Peace Movement do not.
As you can see, we can actually have quite a strong (by NZDF standards, that is) presence within that area if desired. And given this is conducted within the Five Power framework, it wouldn't even attract huge headlines like "NZ joins with Indo-Pacific Quad" or "Five Eyes battlegroup challenges China" - because it has been happening within the existing regional alliance structure, and China is well aware of it happening ahead of time.
But to go back to your actual question - should NZ take a stronger stance? Ultimately I can't answer that accurately without being aware of information that simply isn't public, regarding what officials consider a potential risk to creating a dangerous situation or confrontation, compared to a simple protest or military exercise considered routine rather than provocative.
But overall, I think we are getting a bit away from the point of this thread - the idea of whether UKUSA, or some other arrangement - would work well as a platform for raising concerns over China's recent actions alongside other international partners. UKUSA is in my view (and the Government's) a ridiculous framework due to the intelligence focus alone, and it exclude other countries. The EU, UK, US and Canada jointly sanctioned China recenty, so we also can't just look at one resolution and assess which countries would or wouldn't be likely to work collaboratively under such conditions. Diplomacy is a complex system of connections between countries, and while the EU is perhaps like-minded in terms of values, ASEAN countries are also closely connected in other areas of immense relevance to the Pacific (trade, security, etc).
What do you think, may I ask? I've actually quite enjoyed this discussion - best of this post so far. How do you think NZ should best act moving forward on these issues?