His mother Pamela, 71, had earlier condemned the verdict as a "joke".
"I saw the CCTV footage in court and you can see that Andrew didn't cause Lewis Gill any harm," she told Bournemouth News and Picture Service press agency.
"I sat with him when he died. I wish that awful man who took my son away had pleaded not guilty so he would have got a longer sentence.
"The sentence is an absolute joke. I'm a committed Christian but I think that if someone takes a life they should be prepared to forfeit their own.
"There have been many people who have committed manslaughter or murder in this country and they never even serve a full sentence."
On Wednesday the Attorney General's Office tweeted that it had received a number of requests to review the sentence.
"Have received a number of requests to review the manslaughter sentence of Lewis Gill. Only takes one request and process now started," it said.
Dominic Grieve has until 21 March to decide whether to refer the sentence to the Court of Appeal.
A statement made by Mr Young's family said they were pleased the sentence was being looked at again.
"When we first heard that Gill was given a four year sentence we thought it was too short and expected him to get more than that. It's ridiculous," it said.
"He (Gill) didn't mean to kill him so a life sentence would have been extreme but he deserves more than what he was given.
"Looking at his criminal record he is obviously a trouble maker and we were hoping he would get about seven or eight years.
"A sentence so short might mean that he could do something else dangerous in the future.
"We are pleased that the Attorney General is reviewing the sentence as people like that never really seem to learn."
Released CCTV footage shows the attack, which took place outside the Tesco Metro store on Charminster Road, Bournemouth, at 4.25pm on 6 November last year.
The video shows Mr Young talking to an acquaintance of Gill's about his cycling on the pavement.
The cyclist rides off, but moments later Gill is seen punching Mr Young in the face without provocation, the court was told.
Mr Young is seen falling backwards and striking his head on the road.
Gill, from Sutton, Surrey, is then seen walking away as Mr Young remains motionless on the ground.
He died the next day at Southampton hospital.
Gill pleaded guilty to manslaughter.
Steven Perian, defending, said Gill had felt threatened by Mr Young, but judge Keith Cutler rejected the claim.
In passing sentence, Judge Cutler explained why he was sentencing Gill to only four years.
He said: "What I have had to look at is what was in your mind at the time you threw that punch.
"You wanted to cause some injury to Mr Young. If you wanted to cause grievous bodily harm it would have been a murder charge.
"I bear in mind your early guilty plea. I accept there is no pre-meditated element and provocation does exist."
Gill was also sentenced to two three-month prison terms to run consecutively after committing the crime while on a suspended sentence for robbery and for handling stolen goods.
- UK Independent
