I'm just hoping that NZF got the proper permission from FIFA for Wynn to play for the All Whites and u-20's.
If FIFA gave NZF permission, then he will in fact be eligible for the Olympic qualifiers too...
Which year did Wynn immigrate to NZ?
It would be an interesting exercise to look at the players in the recent u-20 World Cup to see if any had changed nationality and not lived in the new country for at least five years.
Here are all the squads and players on Wiki:
https://en.wikipedia.org/wiki/2015_FIFA_U-20_World_Cup_squads
After clicking on USA team and then Zelalem I see he actually was born in Germany, immigrated to USA in 2006 and went to Arsenal in 2013 - so he lived in USA for more than five years...