Therle and his girlfriend, Lisa Charlotte Simone Elise Peronnet, 30, first came into contact with their teenage victim Tobias Waring in 2018 in Dunedin through a Facebook page offering small amounts of cannabis to French travellers in New Zealand.
They agreed on a price of $400 for the drugs but after the cash was handed over, the teen failed to deliver the goods.
So Therle orchestrated another meeting in August and took out his frustrations on the victim.
The defendant put him in a "headlock", the court heard at sentencing, and punched Waring more than a dozen times.
Therle dragged the man along Duke St towards his van where Peronnet was waiting.
Waring, however, managed to break free as she grabbed at him. He ran to a nearby dairy, his shirt ripped off and his upper body covered in cuts and grazes.
Therle got seven months' home detention and Peronnet, who pleaded guilty to assault, received 100 hours' community work.
The court heard this week she had finished that sentence and been allowed to remain in the country to support her boyfriend.
Counsel Judith Ablett-Kerr QC said the couple had been struggling.
Their rent of $350 a week and other costs were being covered by friends and family.
Therle was desperate to avoid the "indignity" of deportation, Judge Crosbie said, though it appeared from Immigration New Zealand that it would allow the pair to return home unescorted.
The judge said the difficulties of serving home detention were foreseen by him at sentencing.
He described the penalty as "merciful" and noted that higher courts had continually stressed the sentence should be seen as serious and not a soft option compared to incarceration.
For those who might suggest Therle had only a short period left to serve, Judge Crosbie's response was unequivocal.
"The sentence wasn't arrived at as an approximation."
Therle's sentence ends on March 7.
