Temporary exception with an expiration date specified means not allowed after that time. They will not be allowed to board at WLG. There are still some international flights operating from AKL to US, for example Air NZ to HOU (also to YVR but think you can't enter US from Canada now even for US citizens, not sure). EK would be your best bet, via DXB. In a few days options for travel will be even more limited. Lots of countries are now banning transit pax at their airports.