Haisem Zahab, who was arrested in March 2017, pleaded guilty in October, 2018 to knowingly providing support or resources to a terrorist organisation.

Zahab, 44, researched and used 3D technology to develop the mechanical design of a laser warning receiver that provides notice of incoming laser-guided weapons.

He created a report on the receiver and sent it via secure software to a British national who later admitted to being a member of IS. He also simulated flights of rockets, some wrapped in Islamic State's black flag with white writing.

Zahab, an Australian citizen, also admitted to failing to comply with an order to assist access by police to encrypted data on his phone and other devices.

In reaction to the sentence, former Young mayor and current Hilltops Council mayor Brian Ingram said: "In the world we live in today, there are threats at all different levels in a lot of places.

"No one was in any danger in our community and we had to let the police and the taskforce do their investigations and carry out their duties."

Asked about his thoughts on the sentence, Cr Ingram said the judicial system ran its course and treated the matter as it should be.

"It's not really up to me to say whether it's sufficient or not, but as a community, we need to accept the judge's decision," he said.

Cr Ingram said he was surprised about the incident at the time of the arrest.

"I said this could occur anywhere, but we needed to stay calm and treat it for what it was," he said.

Cr Ingram said the "silly comments" on social media at the time were not a true representation of the Muslim community in Young.

"We're very fortunate where we live that we're very multicultural and we have people in the right places to ensure that our communities are safe and remain safe," he said.

Asked about the potential of Zahab returning to Young after his release, the mayor said it was premature to comment about it.

"We're jumping ahead with that," he said.

"No one knows what's going to happen when that time is served.

"I've got my own private thoughts but that's what they are - private thoughts."

Representatives at Young Multicultural Association and at Young Mosque did not respond to requests for comment.

In court on Friday, Zahab said he had resiled from his extremist views.

At a previous hearing, he told the NSW Supreme Court that the "nail in the coffin" for his dwindling support of Islamic State was the bombings carried out on churches and luxury hotels in Sri Lanka on Easter Sunday this year, in which more than 250 people died.

NSW Supreme Court Justice Geoffrey Bellew on Friday jailed Zahab for nine years with a non-parole period of six years and nine months.

Family members gasped and cried out in the public gallery as the sentence was handed down.

Justice Bellew described Zahab's nightly research as secretive and sophisticated, carried out "with unwavering focus, at all times intent upon assisting IS in its involvement in armed and violent hostilities overseas".

Justice Bellew rejected Zahab's claim he genuinely believed IS was "a force of good" at the time of his offending, describing the proposition as "fanciful in the extreme". The judge was also sceptical of his subsequent contrition.

Outside court, Tarek Zahab told reporters he did not think his brother was radicalised.

He said his brother's testimony at his sentence hearing in May to "categorically reject the evil of IS" had put him in danger in Goulburn's Supermax jail.

"The guy has come out on record - which is very, very difficult. It's a vicious group," he said.

"He's pretty much put himself and his life on the line."

Zahab's sentence was backdated to his arrest in early 2017, meaning he will be eligible for parole in December 2023.

- with AAP