Samuel Richard Scott threw the punch which knocked Mr Munro (18) to the ground causing his fatal injuries early on March 6, 2005.
Mr Scott was not charged in relation to the death and was granted interim name suppression until this morning when Coroner David Crerar released his findings on the death.
"It is now clear that Sam Scott ought not to have responded to the insults and assaults by Nicholas Munro in the manner in which he did,'' Coroner Crerar said.
"His reaction was out of proportion to the threat posed to him by Nicholas Munro who was a lot smaller than Sam Scott and was very drunk. The punch which Sam Scott administered was unfortunate in that it had consequences which could not have been anticipated.''
Mr Munro died five days later in Dunedin Hospital from cardiac failure caused by his severe head injuries.
He was drinking with friends and his sister in the hours before the altercation outside a Frederick St bar.
Mr Munro and Mr Scott argued over a taxi.
The pair traded insults and became involved in a scuffle. That settled, but further verbal barbs led to Mr Munro throwing a flurry of ineffectual punches at Mr Scott.
Mr Scott responded by throwing a punch which rendered Mr Munro unconscious or dazed and disorientated. Mr Munro fell to the ground, hitting his head heavily on the road.
Police investigated the matter and did not believe charges were justified. At the insistence of Mr Munro's father, John Munro, Detective Senior Sergeant Kallum Croudis reviewed the investigation and reached the same conclusion.
The Independent Police Conduct Authority investigated the police response and cleared any officers involved of wrongdoing.
Coroner Crerar supported the police investigation's finding.
He extended his sympathy to the family of Mr Munro and declined an order to suppress details of Mr Scott.
