His London nomination was yesterday endorsed by the NZOC. Rather than being chastened by the experience, Campbell said his selection was proof of the quality of people at the organisation.
"Even though the business I was involved in, some people might not agree with it, they're a big enough organisation and big enough people to say 'hey, he's the best in the sport, he deserves to go, we're going to send him'," Campbell said.
After taking a break from the sport following Beijing, Campbell returned in 2009, though it took him a while to win his spot back in the national team and be eligible for the funding that came with it.
"I know how good I am and knew I could get back to being the best in New Zealand pretty easily," he said. "It was just whether the people at Taekwondo New Zealand and the Olympic Committee would send me."
Campbell, who has dyslexia, trains while working part-time at his father's second-hand furniture business.
A change in the way taekwondo will be officiated has given him increased hope of a good result at London. Whereas judges used to score the bouts, each scoring kick will now be recorded electronically via foot and body pads. It will, he said, take away some of the inherent bias shown towards fighters from traditional taekwondo countries. Also, kicks to the head are now worth three as opposed to one to the body. A hook kick, or spinning round-house kick, will gain an extra point.
"You get rewarded for using harder techniques whereas it wasn't worth it in the past because you put so much energy into little reward.
"It's way more exciting. They've put the art back into martial art."
Campbell will be joined in London by 22-year-old Aucklander Vaughn Scott, who will compete in the under-80kg weight division, and Robin Cheong in the under-57kg class.
Scott took up the sport only eight years ago and recent performances would have him ranked 11th in the Olympic field.
Master Jin Keun Oh, national team head coach for Taekwondo NZ, said Scott had outstanding talent. "Vaughn is young and has improved fast in the sport," he said.
Scott, whose mother holds a third-dan black belt in karate, says he will give his first fight his all. "From 16 athletes in the Olympic first round, half will get knocked out," he said. "I've got to treat every fight as if it's my last."
Scott moved to New Zealand when he was eight and says his mother suggested he try the sport as a 14-year-old. "She thought it would keep me out of trouble," he said with a smile.
Cheong is New Zealand's strongest performing taekwondo athlete and sits at seventh in international rankings.
She competed in the under-49kg class at the Beijing Olympic Games, finishing with an Olympic Diploma in seventh place.