The man alleges Jones repeatedly kissed him without consent in a lift at his home and workplace and groped him in a car and at an event over a five-month period when they worked together.
Jones, now 85, has pleaded not guilty to 22 charges of indecent assault and sexual touching without consent against six men between 2003 and 2023 in Sydney and the NSW Southern Highlands.
The former radio staffer previously told the court he confided in 2GB radio host Ray Hadley about the alleged indecent assaults years later.
Hadley, sworn to secrecy, put him in touch with journalist Peter FitzSimons, who was researching similar allegations about Jones, the court was told.
In her opening statement, Jones's barrister Gabrielle Bashir SC suggested the former radio staffer had been encouraged by Hadley to make a complaint against Jones to "destroy" his rival.
Under cross-examination, the former radio staffer accepted Jones had been under pressure at 2GB at the time he made the complaint.
The conservative commentator was the subject of a campaign targeting advertisers as a result of "something stupid" he said on air, the staffer said.
The former Wallabies coach had recently re-signed as the host of 2GB's influential and high-rating breakfast slot at the time.
The former radio staffer said he didn't know if Hadley coveted the slot and didn't recall the 2GB host saying he was unhappy with that announcement.
"I know they didn't like each other but they weren't rivals," he told the court.
He later characterised tensions between the prominent broadcasters as "beef", while denying he came forward to benefit Hadley.
The former radio staffer emphasised he withheld any identifying information from FitzSimons and declined to speak publicly.
"If I wanted to damage (Jones) in any way, wouldn't I want (my allegations) to be made public?" he asked.
He said he wanted FitzSimons to know there was truth to the claims but had insisted on anonymity because he was terrified of the repercussions from Jones.
Hadley and FitzSimons are expected to give evidence next week.
The former radio staffer said Jones previously reprimanded, yelled at, and intimidated him but became "a lot nicer" after groping his groin in the car.
"Once the sexual behaviour began, he was nicer to me," he said.
"I was obviously intimidated but the yelling stopped."
The former radio staffer maintained he would not have been able to push Jones away under any circumstances "given the power dynamic between us".
He told the court he had been groomed by Jones to text him in an intimate manner, heatedly dismissing Ms Bashir's suggestion that grooming happens to children.
"Grooming is secretive behaviour that makes you feel you need to behave in a certain way and you were taught to act in a certain way," the former staffer said.
"That used to happen because he used to touch me on the penis."
When he sent Jones a retirement message thanking him for his "tremendous generosity", the former radio staffer said it was a way of paying tribute.
"He was still a very, very powerful person," he said.
"If I didn't, it would have blown back on me at some point in the future that I was ungrateful."
Ms Bashir has accused the former radio staffer of rewriting his history with Jones.
Jones has denied all of the alleged indecent assaults, which are alleged to have occurred during the latter part of his 35-year broadcasting career, when he dominated Sydney's airwaves.
None of the charges allege grooming.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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