Steve Skelton said the Maid Marian route on Marian Peak, which Conor Smith (22) and Sarwan Chand (27) were attempting when they died in a fall on April 22, 2017, was a "very committing place to be".
Mr Skelton was giving evidence on the second day of the inquest into the pair's death, which is being overseen by coroner David Robinson in the Queenstown District Court.
He said Mr Smith had "exceptional qualifications", but the route was extremely challenging.
"It's conditional, it's committing, it's dark, it's long, and it's only been climbed a few times.
"I don't think he should've been on there."
When asked about his comment to a newspaper after the pair's death that the NZAT instilled "outsized confidence" in its mentees, he said "put yourself in the shoes of a 24-year-old aspiring alpinist".
"You really want to make a name for yourself."
One reason young climbers wanted to be on the team was because of its high public profile.
He had gained the impression the team's mentors could encourage young climbers to "push themselves outside of what their capabilities might be".
Another Queenstown climber, Josh Greer, who frequently climbed with Mr Smith, said his friend had a "strong attitude" towards safety.
"He prioritised it. He wasn't someone who cut corners."
