The "original wording" of Shane's statement was not as it has been posted here. Indeed, the whole watching porn thing did not even arise until April 2004, so it couldn't possibly have been mentioned in any of the original statements.
Shane's first statement was pretty straightforward - it was just an ordinary evening until he heard Jodi was missing, and then within a couple of hours, that she was dead. He had no recollection of the earlier part of the evening - nothing unusual had happened, so nothing stood out for him. Initially, he said that Luke had "probably" been in, because Luke cooked the dinner, so Shane assumed he would have done so on the Monday evening - he just couldn't remember anything about it. He had forgotten that was the evening he had stopped of at a friend's on the way home from work - it was the police who reminded him when they were questioning various phone calls Shane had made from his mobile phone on the Monday evening. There was never, ever, any suggestion that it was "sinister" that Shane had forgotten this visit, yet when Corinne reminded him that there had been something that made Monday's dinner memorable - Luke had burned it - this was claimed to be a "change of story."
The police questioning of Shane was in the same vein as the questioning of Luke - the questioning that three appeal court judges called "outrageous and to be deplored" - I have seen the interviews, and Shane was hauled from pillar to post by officers who had no interest in his answers, they just wanted to have him on record saying certain things. One officer repeatedly tells him "I'm not accepting can't remember, that won't do, you'll have to do better than that." How can anyone "do better than that" if the honest answer is "I don't remember." Shane did not say, in any of those early interviews, that Luke was "not in." Nor did he say that he "did not see Luke." He said, over and over again, that he could not remember any specifics about that evening, including if he'd seen Luke, or where he'd seen him in the house.
The whole humiliation of having him admit to masturbating was done at trial - that had been part of any of the earlier interviews - the interrogation of April 2004 covered the fact that they had "found out" he had been "looking at porn sites" - and whether he worried whether anyone would come into his room when he was doing so. Alan Turnbull QC took it to a whole new level, to utterly humiliate the witness and destroy his credibility.