Wainwright told the court the first time he saw the pou he was with a friend whose reaction on seeing the pou was to say 'that's disgusting."
He recounted another incident during which he saw a young girl sitting on the shoulders of the pou while a young boy was touching the penis on the pou.
"I wondered what was going to happen to children who were exposed to this type of indecency."
The court was told he had complained by email about the pou to Tararua mayor Tracey Collis, Department of Conservation staff and police but no action was taken.
Responding to Wainwright's complaint Collis told him not to take any action as this would be highly offensive to Rangitane and would land him in trouble with the law.
In a police interview Wainwright told Constable Timothy White had been on the track and as he was leaving he noticed his was the only vehicle left in the carpark h felt strongly compelled to do something about the pou.
He removed a handsaw from his vehicle and set about sawing off the penis, but he said the wood was too hard so he returned the following morning with his chainsaw and completed the removal.
"I was very careful not to damage the legs as I didn't want to show any disrespect."
The following day Wainwright contacted Collis and DoC to notify them of what he had done.
Judge Lance Rowe said Wainwright was offended by the fact the pou had a prominently displayed penis, but he said represented the fertility Rangitane had bestowed in terms of his iwi and descendants.
"Mr Wainwright knew the act he was undertaking was unlawful and he acknowledged he would be subject to a penalty if the acted to make the pou decent. He acted on what he considered to be a moral imperative but that is not available to him as a defence in law.
"The defence is formed on a purely subjective basis and that can become a mask for anarchy, for people to take the law into their own hands through a sense of morality and on that basis can also become a mask for intolerance."
Wainwright agreed to attend restorative justice and meet with those affected by his offence.
Judge Rowe said he hoped Wainwright would listen carefully to how this had affected them and that it instills in him a sense of responsibilityu for what he had done.
He will be sentenced on September 12.