Jason, this story has been doing the rounds for quite a while. It seems to have originated from Mick Gledhill 'the name caller' on one of the 'Show Me the Money' podcasts.
Since then the rumour has been repeated by the usual RL online publications, in particular, Serious About Rugby League (SARL) who repeat it every few weeks when there is nothing else for them them to 'report' upon. Each time SARL use the story they use a misleading headline which gives the indication that it is new story or breaking news. Its nothing of the sort, its just the same old story doing the rounds.
I use the word 'report' advisedly since for SARL this basically means regurgitating other publications' stories and trying to pass them off as their own by just changing a few words. SARL is not worthy of the name journalism. Its more a case of 'cut and paste'.
Anyhow, the 'big NRL signing story' has been around for a number of weeks with nothing further being added. The speculation is from fans that the signing will be a half back. I've seen nothing more definite than this. If, however, anyone else has seen more then please feel free to put your two penneth in. However, i for one would not bet against there being a big signing announced and playing for us before the end of this season.