He appeared before the Parole Board for the first time this month with the decision released to the Herald today.
Panel Convenor Tania Williams Blyth said Simpson had been a "significant player" in the operation.
"At that time, he was a practising lawyer and the architect of a money-laundering process designed to generate significant funds for the Comancheros gang," she said.
"Mr Simpson structured the money-laundering scheme over multiple trust accounts and deposited money himself on occasion."
Justice Gerard van Bohemen had commented at sentencing that Simpson knew what he was doing was "dodgy", she said.
Intercepted calls showed Simpson had advised a key money handler in the plot to keep any cash deposits under $10,000 to avoid alerting the banks, which are obliged to report any transactions above the threshold as suspicious.
The calls, played during the recent High Court trial of the gang's boss Pasilika Naufahu, had aired discussions about dropping nine "apples" in baskets at a time.
Simpson said if the deposits went into his trust account "[the banks] will happily take it".
"They will ask for your ID but it is not going to get flagged," he said.
The Parole Board noted it had received letters of support that referenced Simpson's Christian beliefs and positive character.
"This is clearly at odds with his dishonest behaviour and significant role as architect and facilitator of the money-laundering scheme," Williams Blyth said.
The Parole Board also heard he hopes to return to practising law as he claims he is "good at it".
"This comment fails to recognise that his dishonest behaviour was not that of a lawyer who is good at their job," Williams Blyth said.
The board was not satisfied Simpson no longer poses an undue risk and parole was declined.
His case will be considered again later this year.
