Gardner was ordered to attend the STOP sex offender programme in Christchurch as part of his sentence but the court heard yesterday he was evicted because of his negative attitude.
Judge Kevin Phillips noted the man thought his offending was less severe than others in the group and became disengaged.
Untreated for his sexual predilections, Gardner was again before the court in 2010 for grooming.
Yesterday, the court heard the defendant initially came to the attention of Canadian authorities for his conduct on a chat website under the username "tkoguynz".
Gardner used the site from early 2018 to conduct "age-play", which involves two or more users fabricating an illegal scenario with a child, then describing the sexual liaison.
"It's clear this age-play can promote sexual exploitation of young persons and children," the judge said.
Gardner would ask other users to pose as girls between the ages of 8 and 13, then they would commence the role play.
When New Zealand authorities raided the defendant's home he shared with his mother, they seized electronics which cast further light on his activities.
Gardner, forensic analysts found, had also been using a social-media platform to commit similar offending.
Over three months in mid-2018, he asked 96 users to participate in age-play — 12 agreed.
Gardner pretended to be a male neighbour or a priest and prompted others to act as a "cute and curious" 9-year-old, for example, whom he would describe violating.
The court heard the man outlined graphic sex acts that would continue despite the victim feeling pain.
During that period, Gardner conducted such discussions with three people under the age of 16, Judge Phillips said.
Police discovered many files with photos of naked adolescent females, two objectionable and one with girls as young as 6.
Gardner described age-play as an "escape" and "safe option".
He claimed to have made attempts to ascertain whether it was legal but admitted his efforts were not exhaustive.
A psychological report found sexual preoccupation, sexual entitlement and impulsivity had all likely played a role in the crimes.
Gardner was assessed as a high risk of future offending according to a test.
The judge was not surprised, since the defendant had never completed any treatment for his predilections.
Because of the imposition of imprisonment on two charges of possessing objectionable publication, two of making objectionable publications and one of exposing an under-16 to indecent material, the defendant will automatically be placed on the Child Sex Offender Register.
