I don't think it's about what he could have gained,it's about what he didn't want to give away.He is clearly keeping TR in he dark by leaving JR out of the scenario,and by saying things like Patsy disposed of the cord and tape in a nearby sewer or neighbor's trash.
Of course he put in the book that JR asked for his golf bag,and that PP raided the house.But by not identifying one or the other as to what evidence he thinks went where,he's not giving anything away.That is truly up to the reader to decide.
I imagine TR thought they'd get to gain some insight into what LE truly thought or had evidence of, when Thomas' book came out.And surely JR was prepared with numerous excuses in DOI,but,it didn't happen.
I do think he dropped several hints though,but as I said,for the reader to discern.Things like JB crying and saying she 'didn't feel pretty',that she had seen the school nurse several times that month,and always on a Mon.,and that the word incest had been looked up in the dictionary.
Of course you have those in the investigation saying they thought she'd been subjected to sexual contact,and then Thomas saying he thought it was some sort of corporal punishment being metered out by Patsy.
The most interesting thing to me is that Thomas and Mark Fuhrman went through the evidence together,and Furhman later says it was 'not an accident,in fact,it was quite intentional'.And Thomas says it was an accident,at least up until the cord was placed around her neck.
To me,that says it was not an accident,right from the beginning.If so,then why did Fuhrman fill in the word 'accident' with 'intentional'?