In March, the teen sparked fear after posting a comment on the Australian Islamic House’s Instagram page.
“I’m going to Christchurch 2.0 this joint,” it read.
The comment appearing to reference a repeat of the 2019 Christchurch terror attack, when 51 people were shot dead in New Zealand.
Police launched a nationwide investigation before arresting the boy at his Eaton home near Bunbury, 4000 kilometers from the Sydney mosque.
He was charged with creating false apprehension to the existence of threats or danger.
Officers found videos of the New Zealand shooting after seizing his mobile phone.
They also uncovered a black ski mask, which police say is like the one worn by the Christchurch attacker.
The boy at the time said his comment was just a joke.
But the magistrate today did not find any humour.
“Your actions have caused fear in a community already on edge,” they said.
The teenager, who accepted responsibility in court, must now compete a national countering violence extremism program.