Actually you are wrong there Sebby
There was an outcry when they started the London base.
Only problem was no-one was listening. There was the concern that it was taking jobs away from kiwis and that it would also set a bad precedent.
The other trhing that is different with Shanhai is that NZ based crew were invited to apply for secondment to the London base, but this has not happened in Shanghai.
Also from the news in NZ you will see that chinese applicants did apply for CC postions in Auckland but were rejected and advised they could however take up positions in Shanghai. This goes against your argument of having a shortage of language qualified crew in NZ.
Air NZ has historically rostered only one or two CC per flight on language specific flights, so would have sufficient numbers right now to operate these flights with NZ based crew. In addition figures have shown that there are a large proportion of Westerners traveling this route which negates any need for predominantly Chinese crew. That is also highlighted on the Japanese sectors where there are often only a handful of western pax, yet still only one or two Japanese crew.
This can only been seen as an attempt to reduce cost and has absolutely nothing to do with meeting the cultural requirements of the chinese.