Storm teammate Felise Kaufusi also leapt to the defence of Slater on Monday in response to being taken to task by rugby league legends Brad Fittler and Peter Sterling over the weekend.

Slater has twice been at the centre of professional fouls this year after he fell to the ground after seemingly light contact with Cronulla's Luke Lewis in round four before a similar incident with Newcastle's Lachlan Fitzgibbon on Friday night.

Under NRL rules, referees deem a player has committed a professional foul if he "interferes" with a player after he has taken a quick tap.

On both occasions the opposition players were sent to the bin following the contact, but Fitzgibbon's teammate Heighington believes referees needed to be aware of the matter.

"If he (Slater) can get away with it why not do it. It's one of those things - the refs probably have to crack down on it," Heighington told reporters in Newcastle.

"At the time out on the field I felt pretty hard done by, but that's the rules and you've got to stick by them.

"He got away with one the week before so I thought they could have been onto it a bit more.

"It was a weak penalty and you get 10 minutes without a player on the field. I don't think it's right."

Fitzgibbon wasn't willing to be as critical, accepting his fault in the matter after he put his hands on Slater in an offside position as he took the quick tap in the 40-14 loss.

"Billy Slater is a legend of our game. He's a competitor and he does anything to win," Fitzgibbon said.

"The rules are rules. Outside the 10 players are allowed a quick tap and I put a hand on Slater.

"If that's what the refs are calling and are going to play by then I'm fine with it."

However Sterling wasn't so lenient, labelling it "embarrassing" for the two-time Clive Churchill Medal winner.

It prompted Kaufusi to come to the 34-year-old's defence at Storm training on Monday.

"I'm sure Billy doesn't do that on purpose ... given the circumstances of the game it might have looked worse than it was," Kaufusi said.

"Billy's a great player. He's got the best interests of the game (at heart).

"He doesn't want to be doing anything cheap like that, so I'm not sure what you put (that criticism) down to."

Australian Associated Press