Less than 12 hours after allegedly calling Thurston a "f***wit", Leniu took to social media on Saturday morning to accuse him of being two-faced and "fake".
AAP understands the NRL is not yet investigating the issue and will not do so unless the Nine Network or Thurston makes a formal complaint and presents them with evidence.
At this stage, neither Nine nor Thurston have made any complaint.
Friday night's sideline drama continued the ugly fall out from last year's Las Vegas racism saga, where Leniu admitted to calling Indigenous star Ezra Mam a monkey.
Leniu was subsequently handed an eight-game ban, while Thurston at the time called for blanket 12-match suspensions for any player found guilty of a racial slur.
Leniu first clashed with Thurston while being interchanged during the second half of the Roosters' 26-16 win over Brisbane on Friday night, with Thurston working sideline for Nine.
AAP understands Thurston approached Leniu after the match to clarify the issue, prompting a second verbal spray.
Thurston is understood to have been rattled by the incident, with sources close to the 41-year-old claiming Leniu called him a "f***wit".
Friday night's match marked the first time Leniu had played the Broncos since the incident, and was booed as he walked from the field before the spat.
The Samoan international then took to Instagram on Saturday morning to hit out at reporting on the affair, before unleashing further shots at Thurston.
"I never wanted to talk to the JT, he kept trying to come speak to me," Leniu posted in a story on the social media site.
"I said 'Lad idc (I don't care) if that you hate me for what I did. But don't come up to me asking me questions like we're Algood (sic).
"Don't be two face (sic). Hate me lad I'm eetswa (sweet) with that. But don't be fake. I hate fake people."
It's understood Leniu had been upset by Thurston speaking about the racial slur on a podcast aired during last year's finals.
Leniu had earlier on Friday been involved in one of the more heated moments of Friday's match, when he launched an off-the-ball hit at Kotoni Staggs after a high tackle.
The Roosters prop was cautioned over the incident, but not sin-binned by referee Peter Gough.
Leniu and Staggs had been involved in a verbal altercation in the corridor of a Las Vegas hotel last year, in the hours after the Mam slur.
Indigenous legend Thurston was due to conduct post-match interviews in the Roosters' sheds, but Nine colleague Cameron Smith replaced him.
Roosters coach Trent Robinson also defended Leniu after the match.
"People are always going to have differences of opinion and you can voice that," Robinson said.
"It is okay to say 'I don't agree with you' both ends. No harm done … so long as people don't cross the line or say the wrong thing.
"From what I saw there was no crossing the line.
"Spencer didn't approach anybody so I don't know why you are putting it on Spencer here."
