Colin Max Behan, 79, may be free in months after being sentenced in Brisbane District Court on Tuesday.
Behan had pleaded guilty to seven offences including the attempted rape of the 10-year-old in the park and procuring a 12-year old girl for sex.
He will be eligible for parole in mid-October after being sentenced to four-and-a-half years imprisonment with 14 months already served.
The mother of a girl Behan tried to exploit said justice had "not at all" been served.
"I was actually pretty gutted," she told reporters outside court.
"What about the children? She has to live in fear for the rest of her life ... it's gut-wrenching."
Behan entered court with a mobility walker and frequently stared down and shook during the hearing.
Judge Carl Heaton paused proceedings multiple times to check if Bevan was still conscious.
Behan engaged in persistent attempts to groom one of the girls and force the other into sex, Judge Heaton heard.
"His offending is abhorrent and should not be tolerated," the crown prosecutor said.
Behan followed the 10-year-old girl in a public park north of Brisbane in February 2025 before making demands and assaulting her.
"She said 'no', but you persisted and offered her $10," Judge Heaton said.
"She felt scared and threatened."
Behan later blamed the girl and claimed she initiated the behaviour.
On a later date Behan had the girl ride on his mobility scooter before attempting to rape her.
Behan in August 2024 sent text messages to a 12-year-old girl asking for her to send "nudes".
"Can you please, I'll do anything," he texted.
Behan later showed a pornographic film while the girl was playing a game on his computer.
"He poses real and substantial risk to the community," the crown prosecutor said.
Defence barrister Sean Franklin said Behan had no prior criminal record except for drink-driving.
"When he read the victim impact statements, he hung his head in shame and said 'I'm so, so, so sorry'," Mr Franklin said.
In sentencing, Judge Heaton said the victims suffered profound consequences that would significantly change the course of their lives.
"The focus is the need to protect children from the predatory proclivities of people such as you," he said.
Outside court, the grooming victim's mother delivered a message for any parole board considering an early release for Behan.
"Don't do it," she said.
Lifeline 13 11 14
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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