At a hearing in April, the man's lawyer said the child had a history of verbal and physical violence.
On the day of the assault, the boy was upset about staying with his father and locked himself in a room. The father unlocked the door and restrained the boy because he feared he would jump out a window.
The child then fell to the ground, striking a heater and injuring his back.
His mother subsequently took the boy to a GP and alerted police. The man was charged with assault on a child under 12 years - later reduced to a summary offences assault.
Mr Davison said his client would plead guilty to spare his troubled son from having to give evidence, and that the intention to "restrain and prevent self-injury or harm" was a "justifiable use of force".
But police prosecutor Brent Thomson argued the incident involved "an excessive use of force".
Judge Paul told the April hearing the picture presented was of a "troubled young boy".
The assault involved "pushing and holding down and bruising". The boy's age increased the seriousness.
"There is a fine line between restraint to prevent self harm and in effect an assault, which cannot be justified," he said, before granting suppression orders which indicated the case could not be reported.
Arguing in court yesterday, Sam Hiebendaal, for APN News & Media, owners of the Herald, said it was not in the district court's jurisdiction to impose such a far-reaching ban.
Judge Paul clarified his previous order, saying it should only extend to identification of the man and the victim.
The order was intended to protect the boy, he said.
