Moving off the mark BEFORE the play of the ball should be a penalty. No doubt.
But after its gone? If he grabs the players maybe but just walking hardly causes a problem. And the fact he could walk between the players shows they were split markers anyway.
Could have been the game breaker if not for the last try.

I don't mind that penalty in general terms- if it's given every time it happens; but it clearly isn't.

As it goes, Fifita did no more than walk between two markers who weren't square, so it was pedantic in the extreme, but that's Mr Child for you - the issue is that he chose not be quite so pedantic for the many other times it happened throughout the match.

I think the problem with moving off the mark is that it is hard to give it consistently and the ref needs to understand playing the game. There were two given today against Salford. on both occasions the Warrington players had hands in the Salford player trying to get up. it might have been that the Salford players were trying to milk a penalty (in which case I am happy with penalties given for that) but they ended up moving forward on their hands and knees with hands on their backs and penalties given. There must have been half a dozen times across the two teams when the player got to their feet took a step or two forward leaving the marker behind them and nothing given. It's harsh to give a penalty when a player slips getting up (esp on a wet pitch like today) or crawls a metre forward with opposition hands on compared to just moving forward when stood up

Whilst I'd be in favour of clamping down on the rules, unfortunately the refs are clamping down on a symptom rather than a cause.

Players are, in general, moving off the mark because they're ready to play the ball but a defender isn't letting them, either intentionally or not. Of course there are instances where it's a genuine attempt to move off the mark and should be penalised but mostly it's just players trying to play the ball and finding a hand or a body of a defender still in the ruck after the tackle has been called by the ref. The natural instinct is to play the ball how you can.

If the refs clamped down on messing around by defenders at the play the ball then this issue would be solved anyway.

Couldn't agree more - there are several areas of the game that would be significantly improved, if the ruck was more robustly policed by the officials; so occasionally penalising a move off the mark, or an acting hb chucking the ball at a prone defender, is only nibbling at the edges.