The now 20-year-old previously went on a hunger strike and during his trial exhibited "bizarre behaviour" including refusing to answer questions when cross-examined and lying under a table.

The offender, who can't be named as he was 16 at the time of the offence, was found guilty at his retrial in April of doing an act or acts between October 6 and October 12 in 2016 in preparation for a terrorist act.

He and his schoolfriend, arrested at a Muslim prayer hall in Bankstown in October 2016, were said to be in joint possession of two M9 bayonets and a sharpener bought for $230 at a nearby gun shop.

The jury at his first trial in 2018 couldn't reach a verdict, but found his schoolfriend guilty and he was jailed for at least 12 years.

The friend had yelled at arresting police: "You're all pigs ... look at you, like lambs to the slaughter ... you will all die in the hellfire at the hands of Allah ... you will be slaughtered at the hands of Allah."

His co-offender, who sacked his lawyer during his retrial, was due to face a sentence hearing on Wednesday in the NSW Supreme Court before Justice Geoffrey Bellew.

The judge was told by Corrective Services that the offender refused to come out of his cell at Goulburn and tried to barricade himself in with a mattress.

He was forced out, stripped of his clothing and forced into the orange jumpsuit required to be worn by those convicted of terror-related offences for security reasons

He said he didn't want to come into court, but the judge asked officers to bring him in if their safety wasn't compromised.

Justice Bellew noted the offender was handcuffed and carried into court by four officers and seated in the dock with them.

"Take me down, I don't want to be here,' he yelled, later saying these were "false proceedings".

Prosecutor Paul Maguire SC agreed that if he voluntarily didn't want to be at his sentence hearing, it was his choice and the judge allowed him to be taken down to the cell.

Mr Maguire referred to a confidential medical report which the offender expressly said he didn't want the judge to see.

Before his lawyer was sacked during the trial, he noted his client did not have a mental illness diagnosis but referred to the possibility of him being on the autism spectrum.

Mr Maguire said the offender had displayed "selective" misbehaviour, sometimes giving coherent and intelligent evidence and standing for the judge and jury.

Since the verdict, the offender refused to take part in an interview with a specialist organised by the Crown.

The offender's father told the judge his son said he did not wish him to speak on his behalf nor did he want the judge to see the medical report.

Justice Bellew noted he had no medical or psychiatric evidence, nor any evidence about prospects of rehabilitation or on whether he had resiled from supporting terrorism.

But he noted he gave the impression of being "an intelligent and articulate young man".

He will be sentenced on November 11.

Australian Associated Press