It's confusing Mr Apples for the agreement was made around him. Ms Lean and "another source" had let the Mitchell's know of an agreement to not use DNA evidence. Nope, it was an agreement to not use DNA as evidence.
The main point of highlighting that agreement is purely to do with deception. Part of that explanation around those ludicrous questions placed such as 'How could it be to not discuss DNA evidence when it was discussed?' The whole basis of blanking the reason is for that purpose, to cause confusion and deflect into what was accepted to not do at trial.
Think of Kelly here, that one profile and the acceptance of trace/diffusion transferal of other parts found. The same applied to Mitchell, that acceptance of the same type of trace transferal. The acceptance that it was NOT stranger DNA, nothing found pointing this murder to 'a another'
Chris points out that each and every sample should be treated in its own merit. Yes, if going through it all piece by piece. Which is something they accepted not to do as it was NOT getting put forward as evidence in the case against Mitchell.
So, the only point in highlighting the technicalities of an agreement, was to say, if there had been nothing and no more of the same, then NO agreement need have been made. It is confusion because the person is actually blanking the actual reason for it. Soley to do with what had been accepted by both sides. And not and never to forget here, those team of bodies who dealt with such matters day in and out. Who would have had experts study the original tests and reports, in turn who gave their expertise around this.
Faith said once, who to trust here? Me or the media, a criminologist and someone who had access to defence papers (more than Joe public). Indeed, who do we trust here? The actual experts who dealt with this case or Joe public in the shape of Ms Lean!
The mangling and manipulation, of Joe public giving their opinion in areas far beyond their reach of understanding. Who claimed they were in a mess, that they could not match samples to reports. Who put a book to print stating the same thing, applied all sorts of conclusions around multiple giant IF's. But has everything of Mitchell's in ship shape fashion, executed perfectly!
The deception to manipulate. The "another source" was directly in front of Mitchell, explained without any doubt fully to him. There is no reason other than deception for NOT knowing the actual details of that agreement.