Ellson then pulled up next to Zajmi in the T3 lane on Remuera Rd and started shouting through his window.
The situation escalated to the pair stopping their cars on the side of the road with Ellson getting out and approaching Zajmi, who had his 2-year-old son in the car with him.
Judge Powell said last month in his ruling on the facts that he was satisfied that by the time Ellson got out of his car, Zajmi wasn't looking for a fight and was primarily concerned for son.
The businessman showed this by parking quite far away from Ellson.
Ellson was also much "taller and heavier" than Zajmi which would have further added to his desire to avoid confrontation, Judge Powell said.
In order to protect himself, Zajmi grabbed a tyre iron which he swung at Ellson after the man tried to punch him.
The judge said he couldn't be sure on the evidence whether the tyre iron connected with Ellson's head in the "road rage incident", but if it did it was "at most" a "glancing blow".
Judge Powell said he was satisfied Zajmi was substantially provoked by Ellson and so at worst his conduct demonstrated "no more than excessive self defence".
Zajmi's lawyer, Jeremy Bioletti, said if his client were to receive a conviction he would not be able to renew his manager's license for one of his cafes and could potentially impact getting a liquor license for his other business.
That would unfairly cause hardship to his wife, family and employees.
Judge Powell said he was satisfied there was a "real and appreciable risk" he would lose the manager's certificate and would be prevented from getting a license for his other cafe.
He said he even doubted whether the charge for which Zajmi pleaded guilty fairly reflected the circumstances.
He granted the discharge without conviction.