Anthony O'Donohue lit a backpack containing a bottle of fuel and threw it inside the bus being driven by Manmeet Alisher while he was collecting passengers in Moorooka, in Brisbane's south, in October 2016.

Queensland's Mental Health Court on Friday declared O'Donohue unfit to stand trial on mental health grounds and ordered he be held in a mental health facility for at least a decade.

Parveen Gupta, lawyer for Mr Alisher's family, say it should be harder for people to use their mental health as a legal defence.

"The laws I think are a bit old," Mr Gupta said.

"They need to be reviewed so that the defence of mental health is available in very, very limited circumstances."

Donohue believed there was a grand conspiracy against him and that people were out to get him at the time of the October 28 attack, the court has heard.

The court was also told that when Mr Alisher smiled at O'Donohue as he boarded the bus he took that as a sign the driver was part of the conspiracy.

Family spokesman Winnerjit Singh and Mr Alisher's longterm friend, Aman Bhangoo, say O'Donohue gamed Australia's justice system.

"He may or he probably has some mental disability, but at the same time he is a very smart guy who has played well with the laws of Australia and he knew what he was doing," Mr Bhangoo said.

"He knew what the action was, he knew what the consequence would be, but he played up using his mental illness."

Pinky Singh, president of the Punjabis Welfare Association in Queensland, says the case demonstrated obvious flaws in the state's mental healthcare system.

She is demanding answers from the Queensland government about why O'Donohue was not given more support.

"People are mentally ill, I do accept that, but what's happening with them?" she said.

"There needs to be a review, maybe there needs to be some sort of system in place in the future so it doesn't happen (again)."

Australian Associated Press