Former state Liberal MP Rory Amon, 36, began his evidence in his NSW Supreme Court trial after pleading not guilty to 10 charges for various sexual acts against the young teen in 2017.
The jury heard Amon had contacted the teenager on Grindr and Snapchat before exchanging explicit photos, including of his erect penis.
But the former politician denies knowing the boy was only 13 when they interacted.
"The question of age was asked ... I do recall he said he was 17," Amon said in court on Friday.
Despite knowing users were not allowed on Grindr when under 18, Amon testified that finding out a prospective match was not an adult was not necessarily an issue for him.
"It was an issue for me (if they were) under 16," he said.
The complainant previously gave evidence that he told Amon he was only 15, but the former politician denied that was the case.
Amon's barrister Matthew Johnston SC asked his client repeatedly whether any of the images or messages he exchanged with the boy gave any indication he was younger than he claimed.
"No ... I would have ceased communication," Amon said.
The 36-year-old testified about his initial guilt and shame from using Grindr as he grappled with his sexuality.
"I was not out sexually until, I guess, now," he said.
By the time the contact with the complainant occurred, Amon was well set for a political career.
He was working full-time for the then-federal MP for Mackellar, Jason Falinski, and campaigning for preselection for upcoming council elections.
He would go on to serve two terms on the Northern Beaches Council before being elected as the Liberal MP for Pittwater in 2023.
Amon is alleged to have met the boy on two occasions in June and July 2017 after speaking on Snapchat.
The sexual activity took place in a communal bathroom connected to the car park in the building where the boy lived, the prosecutor previously told the court.
Now 22, the man told the court he was excited and giddy at meeting Amon, thinking this was the precursor to something romantic.
At the first meeting, the older man wore grey tracksuit pants, a white Adidas hoodie and ugg boots.
After leading the teen into the bathroom, he flushed the toilet and made a comment about the smell before sitting on the floor, the jury was told.
The ex-MP is then accused of placing the boy's hand on his genitals and directing the boy to have sexual intercourse with him.
On a second occasion, that Amon denied happened, the prosecutor said sexual assaults took place while the pair were standing and then laying on a towel brought by Amon.
He allegedly attempted to have sexual intercourse with the teen before telling him to perform another sexual act.
The complainant told his teacher, psychiatrist, parents and friends in 2017 about what allegedly happened.
Amon will continue to give evidence on Monday.
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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