if they get to a point where they can empirically show emissions per kg are way worse then we will lose access to the market

This is a key concern for me. NZ's comparative contribution to carbon emissions between countries doesn't matter much if our trading options become more limited due to current and potential trading partners considering the emissions we produce.

It doesn't necessarily even matter if we're the most efficient producers of those products. We also need to be conscious of possibilities where NZ's primary exports that we rely on so much, like meat and milk, might simply be undermined by more carbon efficient synthetic alternatives as they improve.