Troy Maskell was in 2023 found guilty of manslaughter over the death of John Burke at a Strathmerton service station in northern Victoria.
It was alleged he attacked Mr Burke on August 8, 2021, by hitting him over the head with a one-litre bottle and kicking him on a hard tile floor.
During the trial, the court was told the 73-year-old local postmaster had smiled at Maskell's girlfriend and daughter as they entered the servo.
The woman then wrongly accused Mr Burke of being a pedophile, before the alleged attack occurred.
Mr Burke died in hospital 11 weeks after the attack due to a brain injury.
Maskell was sentenced to eight years in prison with a non-parole period of five years.
He lodged an appeal against his conviction in February 2024, claiming there was a substantial miscarriage of justice.
Victorian Court of Appeal Justices Karin Emerton, Maree Kennedy and Peter Kidd on Friday ruled in Maskell's favour, ordering his conviction be set aside.
The court allowed the appeal on one issue relating to the CCTV shown to the jury during the trial, where Maskell demanded the service station attendant "wipe the tape" following the alleged assault.
Maskell's lawyers argued the footage allowed the jury to make assumptions about his mindset at the time of the alleged attack.
"This invited incriminating conduct reasoning," the judgment read.
"It was inadmissible and introduced in non-compliance with the Jury Directions Act."
CCTV footage of the accused driving into the petrol station before the alleged assault and out of the service station after was also flagged as "irrelevant" by the court.
The justices found the footage of the arrival and departure should have been excluded as his actions in that moment were not in practical dispute.
The court ruled that there had been a substantial miscarriage of justice and Maskell's conviction be set aside and a fresh trial ordered.
The justices dismissed the other two grounds for appeal.
Maskell will return to court in August.
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