The veteran judge described Quinn's desire to attend what Quinn believed was a paedophile party at an LA hotel room and pay a pimp to allow him to rape a young boy as "absolutely disgusting", "ghastly" and "despicable".
Quinn's parents, Anna and John, who had flown in from Australia to support him, sat in the courtroom to his left.
The Monash University-educated IVF geneticist was on a rugby trip to the US when he was arrested. He was set to play with his Melbourne Chargers rugby team in the Bingham Cup in Nashville, Tennessee, a tournament honouring September 11 hero and pioneer of gay rugby clubs, Mark Bingham.
The party at which he was arrested was a sting set up by undercover US authorities who had been communicating with Quinn online for several weeks in Melbourne before his trip.
"Aussie perv, heading to the US late May/June interested to meet others while I'm there. LA, Nashville, NYC," Quinn posted on a social media site used by paedophiles.
A US undercover agent saw the post and began communicating with Quinn. Quinn told him of his wish to rape a boy and authorities set up the sting for when he arrived in LA in May.
Quinn claimed he has never molested a child before his arrest and the sting was the first opportunity offered him.
His lawyer, Lisa Shinar LaBarre, said Quinn's severe addiction to methamphetamine had altered his thinking and created psychotic thoughts. Quinn had also claimed to have been abused as a child. The court heard a psychologist who examined Quinn in jail concluded it was unlikely he would reoffend.
Judge Walter said he was not "overly impressed" by the doctor's report, noting Quinn did not undergo standard testing for paedophilia.
"It upsets me so much that I could be capable of harming a child," Quinn, dressed in a white prison jumpsuit, told the judge.
Quinn also apologised to Australia for "damaging its reputation" and told the court "I never want to put a child in danger again".
Judge Walter said he did not "buy" the cause and effect of Quinn's drug addiction and the abuse he suffered as a child. "The defendant had every intention of raping a boy," the judge said.
The 16-page criminal complaint compiled by US Immigration and Customs Enforcement officer Aaron McClellan, who posed as multiple paedophiles in a sting to capture Quinn, contained disturbing details about the Aussie's sex attack plans.
According to authorities, Quinn had been planning a sexual rendezvous with a six-year-old boy that he kept secret from his travelling companions.
Quinn believed he had been communicating with Los Angeles paedophiles, but it was the undercover ICE agent from the agency's Homeland Security Investigations unit.
"In advance of his travel, Quinn arranged to meet with a small group of like-minded men in the Los Angeles area and go with them to a hotel where they would have sex with children," ICE agent McClellan wrote in the complaint. "Quinn, who expressed preference for boys aged five-10, agreed to pay $US250 an hour to be provided with a child he could sodomise, and suggested sharing a child with one of the other men."
- Additional reporting: AAP
