Mr Kolsen was in a car parked on the side of Te Ngae Rd, talking on his cellphone, when Christensen drove into the back of his vehicle.
The cars spun 180 degrees before coming to rest at the side of the road. Mr Kolsen died at the scene of the crash.
Christensen told police he could not recall how the crash happened.
He said he saw Mr Kolsen's vehicle at the "last instant" and the incident had happened so quickly.
Speaking from Canada after the sentencing yesterday, Mr Kolsen's mother, Lynn Kolsen, told The Daily Post she felt sorry for Christensen.
Miss Kolsen said she last spoke to her only son a week before his death and that if she could have met Christensen she would have told him she forgave him.
"I would have probably asked him to forgive himself, because we have, and that he needs to live his life to the fullest, to not let a burden of guilt ruin his life ... I just don't want to see another life ruined."
Miss Kolsen said the incident involved a split-second of inattention and it could have happened to anyone.
She spoke of her son's 4-year-old twin daughters, Anouk and Katia, and how Anouk was receiving chemotherapy to shrink a non-cancerous tumour on her optic nerve.
The twins' mother, Sara Collins, who lives in Papamoa, told The Daily Post her daughters had their moments when they missed their father, and to cope they would talk to a photograph of him.
The crash scene.
"They tell him everything they've done."
Miss Collins said she had met Christensen and held no animosity towards him.
"He struck me as very sincere about what he was feeling. He was a really nice man ... It was a bit of a freak accident. It was tragic for our family as well as his."
Mr Kolsen's partner, Corinne Lodge, was in court yesterday with their 6-month-old daughter, Alexandria Kolsen-Lodge, who was born six weeks after Mr Kolsen's death.
Outside court she said she didn't think the reparation was enough, given how much it cost to raise a child.
However, she said she had met Christensen at a restorative justice meeting and he appeared genuinely remorseful.
Nick Kolsen
Initially Miss Lodge had not wanted to meet Christensen but decided to for the sake of her daughter.
Miss Lodge said she had wanted Christensen to know her daughter would be growing up without her father.
Judge Phillip Cooper said there was not a high degree of carelessness involved but the consequences were utterly tragic.
"This is a case where it was inattention that caused this crash."
Judge Cooper said Christensen had taken part in two successful restorative justice meetings and had offered to make amends by paying reparation.
"No amount of money can bring Mr Kolsen back ...
"The sum of money will assist the people who have been left behind."
Judge Cooper ordered Christensen to pay $1500 each to Miss Collins and Miss Lodge immediately, and to pay an additional $4160 to each of them at a rate of $40 per week.
Christensen did not want to comment when approached by The Daily Post outside court.