SBM for brevity. How do you know this?
To my knowledge the defense team haven't come out once and said they believe what is said in the affidavit about his combined 'confession' and accusation/allegation.
We know from the affidavit that CW made that allegation. So far, to my knowledge, he is the only person who has made that allegation, not LE, not the DA, and not his defense team.
The defense team may or may not run with that allegation at trial. Even if they do, that doesn't necessarily mean there's evidence to back up the allegation, they could just throw mud and see if any sticks enough for the jury to decide they have doubts and thus not convict on those charges. Running with a particular defense in no way implies the defense team have evidence to back it up nor that they personally believe in it. They can only go with what they're given.
There was a request for CW's handprints that a lot of us conjectured might be to compare marks on necks during autopsy. The defense didn't want to hand them over. Why not? If they believed, from CW, that handing over his handprints would get four counts of murder 1 removed, why wouldn't they be more than willing? I think, from that, they know his handprints won't prove he couldn't have killed the girls and so they'd rather fight the motion than willingly comply and make their job so much simpler to only have the job of trying to get the murder 1 for murdering Shanann reduced to manslaughter or diminished capacity.
Plus, the defense now have the autopsy results. If those autopsy results suggested in any way that Shanann killed the children, then we'd have a possibility of those charges being dropped. Even if they weren't dropped, I think it's a strong possibility that the defense would choose to go before the judge for a bail hearing and argue for bail. In many cases a very high bail is set for murder charges and a defense team will fight for a hearing to get the bail reduced. Even if the accused still can't make the reduced bail I think it has some kind of symbolic meaning?
So for all those reasons, I think the defense are just doing their job right now because it is their job to defend the accused in this case, and there's no sign that they have any evidence with which to accuse Shanann or to back up CW's allegations against Shanann.