"There is also the leadership within the All Blacks as well, which is probably a bigger part of [the decision]."
It is unlikely that Read made a formal request to be considered for Gordon Tietjens' squad, only to be knocked back. A more likely scenario is that a conversation with All Black coach Steve Hansen marking out just how important Read will be in a year of rebuilding for Hansen's team caused him to re-evaluate his options.
Hansen will next year be without McCaw, Dan Carter, Conrad Smith, Ma'a Nonu and Charles Piutau because of retirement or moves overseas. Adding 29-year-old Read to that mix would be unthinkable given the influence he has on the team with his athleticism and handling skills.
It is exactly those characteristics which suggest he would be an outstanding sevens player, but in this case the 15-man team will be the priority.
It is thought that Sonny Bill Williams and Liam Messam are the only All Blacks to have declared an interest in going for gold.
Aaron Cruden has already ruled himself out of contention for the sevens squad, saying he wanted to prepare instead for the 2017 Lions tour of New Zealand.
Cruden's rival for the No10 jersey, Beauden Barrett, is another with the ability to be a devastating sevens player, but Tietjens also wants to reward those already in his squad who have remained loyal without the carrot of an Olympic gold medal.
Tietjens must submit a wider squad to the New Zealand Olympic Committee by August 5. It is understood that up to 26 players will be confirmed in the squad announced after the World Cup. That squad will be reduced to 12 for the Olympics.
Read's focus on the 15-man game will also be welcomed by Crusaders coach Todd Blackadder, who will be without McCaw, Carter and Colin Slade next year.