Allan George Matthews surgically removed the man's testicle in a Port Macquarie motel room in May 2016 after answering an online ad from the victim calling for help to transition gender.

Matthews, 58, was sentenced in Port Macquarie District Court on Friday to a five-year good behaviour bond for recklessly causing grievous bodily harm to the 53-year-old man.

A police investigation began when the younger man presented to hospital a few weeks after the procedure seeking treatment for an infected wound.

The court heard the victim had, from 2013, posted on social media about his desire to transition gender. He said he needed help.

Matthews eventually made contact with the man and the two exchanged a series of text messages.

It was alleged Matthews said he was medically trained and had an extensive medical kit and would be "happy to assist you on your path".

The two arranged to meet in a Port Macquarie motel room for the procedure in mid-May 2016.

After the operation, the two men exchanged a series of text messages regarding the wound seeping.

A fortnight after the removal, the man saw his GP, who recommended he attend hospital.

Staff there realised the procedure hadn't been performed by a qualified person and informed the police.

Detectives subsequently arrested Matthews and searched his Glen Innes home in late June.

They seized medical and electronic equipment, four bottles of what they suspected to be amyl nitrate and firearms.

Matthews later pleaded guilty to recklessly causing grievous bodily harm and removing tissue from the body of another without authority.

He also pleaded guilty to possessing or attempting to prescribe a restricted substance and firearms offences.

Judge Clive Jeffreys on Friday said he'd taken into account the contrition demonstrated by Matthews' guilty pleas.

"It's an unusual case," the judge said.

"There was no payment or favour offered or sought between the offender and the complainant."

Judge Jeffreys said significant media attention meant Matthews had suffered serious loss as a result of the case.

His 38-year career as an aircraft engineer was finished and Matthews now lives in a caravan park in Queensland doing casual work.

Judge Jeffreys said at one short-term job a fellow employee saw a social media post about the case and bashed Matthews.

The judge said he believed the testicle procedure was performed with the consent of the complainant and out of genuine motivation to help with his gender transition.

Matthews' risk of re-offending was low, the court was told.