The Parole Board, which saw 35-year-old Shaan Roker at Otago Corrections Facility last month, said that was an assertion it ''struggled to accept''.
Roker was jailed for six and a-half years before the High Court at Dunedin in July 2017, after pleading guilty to wounding with intent to do grievous bodily harm and assaulting a female.
The Australian citizen - a father of two - had been back in New Zealand only a week and was temporarily living with his ex-partner at Taieri Mouth on the morning of February 21, 2017.
After the pair argued, Roker elbowed his former partner in the head and then hit her with an open hand.
When the victim's father came home two hours later, he ordered the man to leave.
The pair wrestled on the floor of the lounge and the victim gained the upper hand.
Roker left, but soon returned with a machete, which he raised above his head before running at the victim.
The man threw out his left arm to block the blow.
It left his hand hanging by only the skin.
Parole Board convener Judge Geoffrey Ellis noted Roker had no history of violence in New Zealand or Australia.
''The reports before us identify substance abuse, relationship difficulties, propensity to use violence and unhelpful lifestyle balance as underlying risk factors,'' he said.
However, it was unclear whether Roker agreed with that assessment.
The prisoner had completed the Drug Treatment Programme while behind bars and claimed he wanted to also do the Short Rehabilitation Programme.
But when Corrections offered to transfer him to Invercargill Prison to do so, he chose not to make the move.
''We were, frankly, left in doubt as to his motivation and commitment towards that rehabilitative programme,'' Judge Ellis said.
Roker had stable accommodation lined up for his return to Australia but there were major worries for the board.
''What was of concern, after our interaction with Mr Roker, is that we found ourselves in difficulty making any realistic assessment of the level of his risk,'' Judge Ellis said.
A psychological report was ordered. The prisoner will come up for parole again in August.
