"In my judgement it is insufficient for a prisoner to simply write a letter to the victim for the judge to come to the conclusion that the prisoner is genuinely remorseful."
Had Mr Kaukau died, Koloamatangi would have been guilty of manslaughter, he said.
Crown prosecutor James Cairney told the court Koloamatangi's bail breaches had been "extremely frustrating" for the victim and his letter of apology was "a little too late in the piece" to provide him with any solace.
"We have not seen from Mr Koloamatangi any sober assessment of the consequences of his actions."
Mr Cairney submitted that there were no mitigating features "at all" that the judge should consider when imposing a sentence.
Mr Kaukau was still severely brain damaged and would never return to how he once was, he said.
"Mr Kaukau was a community man, a good man who was committed to his family and his community."
Defence counsel Jo Scott asked the judge to take into account Koloamatangi's youth, his early guilty plea, his low risk of re-offending, his lack of relevant previous convictions, and his completion of an alcohol and drug treatment programme.
She submitted that his remorse was genuine, and that a sentence of home detention was appropriate.
There was also a lack of premeditation in the offending.
"When he went out that night he wasn't asking to have a fight ... it was very much a case of trouble coming to him, and he responded badly," she said.
Koloamatangi was at a nightclub on Auckland's K' Rd in the early hours of Saturday June 25.
He went outside for a smoke and met Mr Kaukau.
At a previous hearing, Judge Wade said Mr Kaukau made an "obscene suggestion" to Koloamatangi before the punch was thrown.
"The victim is openly homosexual and, particularly when intoxicated, is in the habit of propositioning other males," he told the court.
Ms Scott said Koloamatangi had responded badly to being sexually propositioned, "like many young males would".
Several of Koloamatangi's relatives sat in court as Judge Wade sentenced him to 12 months imprisonment.
Speaking outside court, Koloamatangi's father Sosaia Koloamatangi said the family accepted the judge's decision to send his son to prison.
"What he did was wrong. We want to say sorry for Trevor. We know that he won't be the same as before and we want to apologise to his family for the hard time that they've been through while Trevor's been in the rehab centre."
Mr Koloamatangi struggled to fight back tears as he spoke about Mr Kaukau.
"We pray for Trevor every night, our family. We know what his family's going through. The judge has stopped us from seeing the victim's family but we still wanted to see them to say sorry."
His son was also "very sorry" for what he had done.
