NZRU boss Steve Tew refused to comment on the situation or give any details about the impasse.
Any explanation was neither fair nor legal, he said, but he acknowledged the issues if Nonu played offshore next season before any further All Black duty. The NZRU had clear eligibility policies involving residency and playing in preceding domestic tournaments.
However the board had discretionary powers, which they had used when Luke McAlister returned from overseas in 2009 and played for the All Blacks.
"At the end of the day we have a very, very firm policy that you have to play in New Zealand to be an All Black.
"We believe that has held us in incredibly good stead in the retention of a lot more players than most people thought we were going to be able to keep playing in this country after particularly the last World Cup."
Injured captain McCaw will fly with the squad to Argentina where the All Blacks will meet the Pumas at La Plata on September 29.
"With Richie we believe that the best chance of having him available to play against South Africa is by having him travel with the squad and getting 'hands-on' treatment from the All Blacks medical staff," Hansen explained.
A decision on whether McCaw will be ready to play the Springboks the following week in Johannesburg will be left as late as possible. If he does not make the deadline, Matt Todd will fly out to join the squad in South Africa.
The squad announcement yesterday confirmed Tom Taylor's selection as a five-eighths replacement for an injured Daniel Carter.
Discussions with former All Black loose forward Jerome Kaino, who is reportedly keen to return to New Zealand from Japan, were continuing.
The test programme for the next two years had been decided and would be released in the next month.
There was a chance the All Blacks could play in San Francisco next year but there was also interest in New York.
Squad: Israel Dagg, Charles Piutau, Julian Savea, Ben Smith, Conrad Smith, Ma'a Nonu, Beauden Barrett, Aaron Cruden, Tom Taylor, Aaron Smith, Tawera Kerr-Barlow, Piri Weepu, Kieran Read, Liam Messam, Richie McCaw, Steven Luatua, Sam Cane, Sam Whitelock, Brodie Retallick, Jeremy Thrush, Tony Woodcock, Owen Franks, Ben Franks, Charlie Faumuina, Wyatt Crockett, Dane Coles, Andrew Hore, Keven Mealamu.