"Without any warning they changed it and 53.90 is beyond achievable," Cull laments.
He says Australia are sticking with the 54.70 B standard qualifying time.
Gearey, 16, will compete in the heats tomorrow and, if she makes the cut, will race in the semifinals and finals on Saturday.
Cull says he's had discussions with Seatter but the former Hastings national representative race walker based in Auckland was adamant making standards tougher was the way to find elite athletes in every track-and-field discipline.
Seatter, he says, has based his argument on research.
"I don't think he [Seatter] understands it.
"That's almost unachievable. Athletes at that age aren't strong.
"If we destroy the base for these youngsters then they'll start talking full scholarships to the American universities rather than staying in New Zealand," Cull says.
Gearey is eligible for the World Juniors this year and in 2016.
If she doesn't make the B standard qualifying time this weekend then she'll have another chance at the New Zealand Junior Championship in Wellington in the last weekend of this month.
She is the No1 400m runner in her age group in the country and is No4 in the senior ranks.
She was runner-up in the Sylvia Potts Classic in Hastings earlier this year and third a week later in the Wellington leg of the national series.
The teenager says she's worked hard but if she doesn't make it this year she won't despair.
"It's quite a lot harder so I'll need to make a big break," the former Puketapu primary and intermediate pupil says.
"My main reason [for going to Sydney] is to get good competition to push me to the limit."
No doubt she'll be over the moon should she qualify for the Junior Worlds.
Her regimented 1hour training regime, every day but Fridays, reflects her determination.
"I'm doing track and hill sprints just to get my legs stronger to get a PB."
However, she has been tapering off her training for the past week to be race worthy.
She takes heart from a 300m PB she set last week of 39.60s. It's an encouraging yardstick to her potential to emulate that feat over an added 100m in Sydney or Wellington.
Last winter she competed in the World Youth Championship in Ukraine where she finished 17th, making it into the semifinals.
"It was a big moment for me because I was competing overseas for the first time," she says. A budding gymnast, Gearey flirted with athletics in year nine at NGHS school meetings.
It wasn't until she became a member for the Ocean Beach Surf Club the following year that she found traction with running.
Fellow NGHS pupil Josie Minor recommended Cull as coach and the rest is history.
Gearey says the demands of athletics meant gymnastics had to go.
"Gymnastics is really involving so you can't do much else," says the youngster who made it to step eight and represented the Bay.
Gymnastics gave her the ideal platform to acquire a threshold of fitness.
Her immediate goals are realistic and the long-term ones equally sobering.
She wants another national age-group title, the under-18 one, and in the process make the World Juniors.
She also accepts she'll be better suited to the 800m event in her early to mid-20s.
"I also want to make the Commonwealth Games relay team but I have plenty of time to do that because I'm still pretty young."
Her school supports her quest and have contingency plans to help her if she lags behind in the classroom but Gearey is up with the play academically.
"At the moment, I'm not worrying much and I'm keeping on top of things."
She comes from a family of soccer players.
Her parents, Evelyn and Ian Gearey are mindful injuries from contact sport will curtail her athletics.
Her twin brother, Joe, is a soccer player at Napier Boys' High School.
Her half brothers, David and Richard Gearey, have also played the beautiful game to an elite level.