The police summary of facts says Bastion and his girlfriend began arguing as they walked past the Queenstown Memorial Centre on Christmas Eve.
It escalated to the point where he was yelling and screaming at her as she lay on the ground in the foetal position.
That prompted a passerby to tell Bastion to leave her alone, and then follow him for a short distance.
However, the defendant turned and punched the man in the face, twice.
When the victim regained his feet, Bastion pushed him over, thrust his face into the pavement and punched him in the back of the head.
A second onlooker then intervened.
Bastion responded by punching him twice in the face, too, and then returned to the first victim.
He grabbed the back of the man's head and punched him three more times with "significant force".
When the second victim again intervened, Bastion punched him twice more in the head.
The attacks on the two men lasted for about 10 minutes, despite repeated attempts by the defendant's girlfriend to restrain him.
Judge Doyle said Bastion was unrelenting in his attacks on the two men, "innocent members of the public acting as Good Samaritans".
He was on special release conditions at the time for other offending.
Bastion admitted two charges of assault with intent to injure, as well as one of assault in a family relationship stemming from an incident at his girlfriend's home on April 25.
The pair had argued the night before and in the morning, when she refused an offer of a sandwich he had made, he threw it and other food at her, and sprayed her with water.
He then pushed her on to the bed, and when she got back to her feet, he grabbed her arms and pushed her against the wall, causing her to hit her head.
That assault occurred while he was on bail for the other two charges.
Taking account of Bastion's early guilty pleas, expression of remorse and willingness to engage in restorative justice, Judge Doyle came to an end sentence of 16 months' prison.
That was converted to eight months' home detention, with conditions enabling intervention for his anger management and drug and alcohol issues.
Post-detention conditions would allow that intervention to continue for a further 12 months.
He must pay each of his male victims $500 reparation.