Prosecuting barrister Simon Wilshire had told the court the question was whether Jackson hit out in anger or in fear of an “imminent attack”.
He argued that Jackson had thrown a “haymaker of a punch” in anger.
Tana Adkin KC, representing Jackson, told jurors what happened was an accident and “pure self-defence”.
She said Jackson was not the aggressor and had not thrown a “haymaker”.
Mr Wallendorf’s wife, Victoria, told the hearing they had been separated.
But, in a victim impact statement, she said the consequences of his death had been “catastrophic”.
“It was the most difficult day of my life,” she added.
“His loss has left a big void.”
Mr Wallendorf’s mother, Sally, told the judge in a victim impact statement that she had gone through a “tragic, senseless nightmare”.
The judge said he did not think that Jackson was a danger to the public.
He also said he had considered the problem of prison overcrowding when deciding to impose a suspended sentence.
Det Ch Insp Nick Gardner, from the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit, said the “whole incident” was tragic.
“It is a silly argument in the car park and it ultimately led to someone losing their life for a decision,” he said.
