Lets get a couple of facts right:
Its not a 28hr flight to NZ, its 12hr max
The NZ record is well under 28min
Jake Robertson has been asked to get him to 6000m in 16:12 which shouldn't be a stretch for big Jake
Salazar is bringing two "non-american squad members" (presumably Kenyans) to help with pacing
The last time a world class meet was held in Christchurch, New Zealand the 10,000m was won in 27:42 and the 1500m in 3:32.....and that was 1974!!!! One of the best places in the world to run a fast time, its hard to understand why more northern hemispherians don't go there in the Southern Summer to race rather than cough up a lung running in germ-filled indoor tracks or sub-zero temperature conditions. Salazar has recognised it.
Rupp will be able to spend time training in 20-25deg celcius conditions while in NZ, on endless forest trails which immediately gives him the jump on those trudging around the snow up north.
Not to mention getting to see a country that few Americans have the sense to visit. Ask anyone who has been, it is the best country on earth.