Leniu was on Sunday (Monday AEDT) hit with a contrary conduct charge, with the NRL referring him straight to the judiciary amid a claim he called Brisbane star Ezra Mam a "monkey".
The Sydney Roosters recruit denied the allegation when placed on report on field by referee Adam Gee, and could be heard to respond "Why would I say that?"
Under NRL rules, the judiciary is not scheduled to meet until Tuesday next week, after the remainder of round one has been completed this weekend.
However, the Roosters can make an application to judiciary chairman Geoff Bellew to have the hearing moved forward to this week, after teams return from the US.
"It was really disappointing to be talking about something of this nature," NRL CEO Andrew Abdo said on Sunday.
"There is no place for discrimination of any kind. We take it very, very seriously.
"I can't talk about the specifics of what happened last night. The player involved involved has been charged and then referred directly to the judiciary.
"We will respect that process and won't make comments."
Ezra Mam says he was racially abused during the NRL's season-opening double-header in Las Vegas. (HANDOUT/NRL PHOTOS)
Tensions between the two teams remained high in the early hours of Sunday morning in Las Vegas, with players exchanging words as they passed each other at the Hilton at Resorts World.
Witnesses told AAP there was no threat of a physical altercation, and Leniu was ushered down the corridor by club staff as words were exchanged. The teams were sharing the same floor at the hotel.
Mam was picked up telling referee Gee "he called me a monkey" late in the second half of the Broncos' 20-10 loss to the Roosters on Saturday night.
The five-eighth told Broncos officials later he was adamant he had heard the remark.
Leniu told Triple M after the match he was not "worried at all", and that the incident was "just fun and games on the field, that's it".
That comment has also drawn the ire of some players, with South Sydney star Cody Walker and Broncos centre Kotoni Staggs among those expressing frustration on social media.
Indigenous All Stars captain Latrell Mitchell has demanded the NRL take action, while posting "typical" alongside a headline detailing the alleged incident.
"I stand with you Bala," Mitchell posted on an Instagram story.
"NRL better deal with this s**t."
The NRL has largely avoided any on-field racial incidents in the past decade, with Mitchell Barnett the last player accused of a slur - by Tyrone Peachey in 2020.
Barnett denied the allegation, and the investigation was closed when a review of footage and audio uncovered no evidence.
Paul Gallen was fined $10,000 for a racial slur against St George Illawarra's Mickey Paea in 2009.
Gallen made a public apology over the incident, and stood down as Cronulla captain.
Warriors winger Marcelo Montoya was suspended for four games in 2022 for a homophobic slur in a match against North Queensland.
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