Gill told the Herald that it was disappointing not to be named.
"There was a 'B' qualifying, set by IAAF, which was 20m. I did that. Then it was set to 20.30m by Athletics New Zealand to try to make it harder and to demonstrate you can make the top 16. I did that. I'm now kind of wondering what I have to do."
In the end, he had to give up his Olympic medal dream for the more achievable, pragmatic goal of retaining his world junior crown and breaking the under-20 world record.
Late last week, Athletics New Zealand high performance director Scott Goodman had an email from the Gills telling him their decision. He asked them to wait until he had a chance to talk through all the options. A two- to three-hour meeting took place at the Gills' North Shore home on Sunday.
"I'm quite convinced Jacko's made a good decision. It's an unusual decision for many people. They'll struggle to come to terms with it," Goodman said. "If he'd gone to the world juniors and Olympics, trying to switch from the 6kg to the 7.26kg shot was going to be a challenge for him."
Goodman said Gill's non-selection was purely a matter of "process" but regretted the way it had been communicated to expectant athletes.
"Logic and common sense says he would have got added at some stage in the next few months. Jacko and Walter understand that, but it's not the same as knowing your name is on the list."
Gill had qualified under the IAAF - the sport's governing body - 'B' standard and the New Zealand Olympic Committee standard.
"The problem is you can only enter one athlete with the 'B' standard ... In fairness to all the athletes on the long list [including shot putter Tom Walsh], they had to wait and see."
Goodman said he could understand why people would struggle to see how Gill could equate competing at the world juniors with the experience gained from competing at the Olympics. But with a career that is expected to stretch well into his 30s, Gill is playing the long game.
"It's a brave decision, but if you step back and think about it, it's a very logical one as well," Goodman said. "He hasn't really had a full season at competing with the open men's implement weight yet.
"The senior men, their average age will be close to 30. There's plenty of guys well into mid-30s - Reece Hoffa and Adam Nelson - so it's a fairly big jump from junior to open men's shot put competition."
Although people were talking up Gill's chance of a medal at London, Athletics NZ's expectations were lower.
"We thought he was realistic top 16 and with some improvement to top 12. That would have made the final and who knows, three throws each, he might have made top eight," Goodman said. "That would have been an outstanding result. For him to have medalled wasn't realistic at this time."
