Fearing for his safety, the victim got back into his vehicle and closed the door.
Ohlson then proceeded to punch the driver's window causing it to smash, and the glass shattered over the victim.
The defendant ran from the scene, but he was arrested a short distance away.
Police said this was an unprovoked attack against someone who was unknown to Ohlson.
The victim suffered cuts and swelling to his left shin, plus minor cuts to his face.
Ohlson's lawyer Coby Martell told Judge David Cameron that her client, who had no prior convictions, was deeply remorseful and ashamed of his actions.
"Because Mr Ohlson was severely intoxicated he cannot recall these events, but nevertheless he accepts responsibility for his behaviour as stated in the police summary," she said.
Martell said Ohlson was sincere in his expressions of remorse and wanted his letter of apology passed to his victim.
Given Ohlson was a first-time offender a sentence of community work and reparation would be the appropriate sanction, she said.
Judge Cameron agreed and sentenced Ohlson to 80 hours' community work and ordered him to pay $250 reparation to the victim.