Trouble with getting Sculthorpe on PAYP is that we have no idea what we'd end up paying him.
We'd still have to leave aside a portion of the salary cap for the eventuality that he might get fit and make some appearances.
Yes if he doesn't play we won't have lost out financially but we will have lost out as we could have spent the money we'd earmarked for Sculthorpe on someone else who would have had more chance of playing.
I read he won't be fit for the start of the season, I think his best hope is a short term deal in the Championship (Featherstone or Halifax, maybe) to try and prove his fitness.