Kikau was on Tuesday night found guilty at the NRL judiciary of endangering Jared Waerea-Hargreaves and banned for one match.
The suspension came after his legal team failed with their argument that the Sydney Roosters prop had contributed by dipping his body and making the situation look worse.
The verdict comes as a blow to Penrith's hopes of playing in their first grand final in 17 years, given Kikau is the most damaging second-rower in the competition.
He leads all second-rowers for tries, linebreaks, linebreak assists and tackle busts this year, but will now miss their clash with the winner of South Sydney and Parramatta.
"While I'm obviously disappointed with the outcome, I respect the decision of the NRL judiciary," Kikau said afterwards.
"I'll now focus on doing everything I can at training to help the team prepare for the preliminary final."
In a 42-minute hearing on Tuesday night, Kikau's lawyer Nick Ghabar also argued that Penrith teammate Jarome Luai had contributed to the end result.
"There was no wrestle in the tackle, but there was an attempt by Waerea-Hargreaves to get to ground as soon as possible," Ghabar told the panel.
"As he does so, he put his left arm on the ground and dives forward, and creates the impression of a lift rather than an actual lift.
"It is Waerea-Hargreaves diving towards the ground that has created this impression.
"Luai drops his own body weight into the equation, so he has contributed to the downward force, further exaggerating the upward motion of Waerea-Hargreaves' legs."
Ghabar also claimed that Kikau had managed Waerea-Hargreaves to the ground in a bid to ensure that the Roosters player's head or neck did not contact the ground.
But it took the three-man judiciary panel of Dallas Johnson, Sean Garlick and Ben Creagh 17 minutes to disagree.
Instead, they believed the NRL's claims that it had largely been Waerea-Hargreaves' actions that stopped the tackle from being far worse.
"He [Kikau] is almost exclusively responsible for this position," NRL counsel Peter McGrath said.
"There is no attempt to stop or arrest that trajectory, causing him to be in a dangerous position.
"He has failed in his duty of care to avoid an injury to the head neck or spine of the attacking player.
"It is as much through the experience and skill of Waerea-Hargreaves to put himself in a position to protect himself, rather than anything Kikau does."
Kikau could have avoided a ban with an early guilty plea, had it not been for two previous charges this year.
He will now likely be replaced in Penrith's starting side by Kurt Capewell, with Spencer Leniu the most likely man to come onto the bench.