"we got dud advice"

So, on the say so of a politically appointed stooge scientist, I see thresholds and limits as published in NZ Standards are no longer legally enforceable?

That's great!  I can ignore the NZS 3604 Building Code when I next build a house and quote the same.  After all I'm sure the local government rort / bureaucracy that surrounds building controls has cost ratepayers somewhat more than $100M.