Mr Duncan still has pain in his knees and has problems sleeping.
Speaking from his sheep and cattle farm in Marton, he described McIlroy's sentence as "tough''.
He said he did not have any ill-feeling towards Ms McIlroy and had written to the court in support of her.
"We're rural people and sh** happens. We're used to dealing with sh** on a daily basis.''
Mr Duncan and three friends had been in Queensland for the weekend before arriving in Auckland. The four friends have shares in a horse, Smoking Chimneys, and had just seen their horse race.
"If we get another one, we're going to call it Smoking Kneecaps.''
The four friends were with their luggage behind a taxi when McIlroy's car lurched forward and hit three of them.
Community Magistrate Philip Greenbank said McIlroy had arrived at the airport to pick up her daughter.
He said she put the car in neutral and as she leaned over to open the passenger door, she knocked her cell phone out of the centre console.
Mr Greenbank said McIlroy then leaned over to pick her phone up off the floor but knocked the gear stick into drive.
Her car lurched forward and hit Mr Duncan and two of his friends.
"The Court's view is that the offending could not be seen to be at the low end of the scale.''
He said he took into account her previously clean record and remorse but said a conviction would not outweigh the seriousness of the offending.
Police prosecutor Sergeant Marty McGahey said McIlroy argued that she may not get her Real Estate Agent's license if she was convicted but there was no evidence of that.
"This is not a minor offence, with respect.''
McIlroy's lawyer Graeme Halse said his client had lived a blameless life and had been driving for 50 years.
He said his client was willing to make a $1000 donation to the Heart Foundation at the request of one of the victims if the discharge without conviction was granted.
In his sentencing, Mr Greenbank said he would not order McIlroy to make a donation to the foundation and it was up to her.
Mr Halse said he would be appealing the sentence.