IANAL, but...thinking of other cases (CA for one)
I wouldn't be at all surprised, however, if her defense fights like hell to get as much of that thrown out as possible--especially if COD doesn't reveal much. I wouldn't be surprised, either, if the attorney uses the JO theory to create doubt. Much like we were all wondering if EG put Lucas where it would implicate JO, I wouldn't be surprised if defense atty at least tries to flip that script.
I think EG leaving Lucas home on Friday will help the prosecution show a lot about EG's attitude to 'parenting' Lucas. History can sometimes be deemed 'prejudicial' but I think in this case it would be valid to bring up those pictures of Lucas with bruises and all the concerned family members who called CPS, because this is all about EG and her treatment of Lucas. They might manage to throw out things like drug history, but I don't think the judge will agree to throw out anything related to Lucas.
The JO theories can be thrown out, I think, as it was EG who led the PI to the body. I also believe there might be forensic evidence in EG's house to show something happened there. It would seem impossible to tie JO to any evidence like that (if it's there). One thing the defense could try is to attempt to throw doubt on EG being the one to cause the bruises on Lucas through abuse, either by saying that Lucas had accidents or by pointing a finger at JH and saying that it could have been either of them. Hopefully dates for JH's work will help. I don't think JH is going to be a very good witness for the defense and the prosecution could use his inactions to throw reasonable doubt on EG being the one to cause the bruises, after all if JH had thought her capable of abusing his son why did he act in the way he did? And a jury will surely find that difficult to understand as well.
Finding a COD and the testimony of the person who saw and interacted with Lucas on the Friday will be very important, imho. That person can say whether Lucas had fresh bruises on his face, and possibly whether Lucas was holding his tummy and saying that he feels sick.
I completely agree that it's not the expected response to waking up and finding a dead child in his bed to go and hide the body instead of calling an ambulance. I think if there's an inconclusive COD that will be another big question. It's a giant sign on EG's forehead that she doesn't care about Lucas' well-being, she doesn't even want to find out how he died, she just wants to hide the body? She doesn't want to check that it's not some bad food she gave him in case it's something she also feed her daughter that day? She calls JH her 'husband' yet she doesn't want him to know his son is dead and how that happened? She doesn't want JH to be able to have an autopsy, answers, and a funeral for his child? She's willing to lie to him, to LE, to media, to everyone...to cover up a natural death?
And if she tries to say she had to hide Lucas' death because she was scared she'd lose visitation with her sons...doesn't that open up questions on why she doesn't have physical custody of her sons? So then the jury learns that she can't be trusted with her own biological children. I feel sorry for whoever gets assigned to 'defend' EG in court.
I am not a lawyer, that's all my own thinking and conjecture. I've only even watched one trial and that was for the death of Bella Bond. Bella's 'mother' had someone in the house at the time, her boyfriend, who she blamed everything on, and it wasn't even a very logical story, but I don't think EG has a good enough scapegoat to do the same thing. Rachelle Bond got off by taking a plea deal to testify against her boyfriend, so her inactions were never put on trial (the inaction of not calling an ambulance for Bella, the inaction of going along with her boyfriend to dump Bella's body, the inaction of sticking with that boyfriend). But I think EG will have to answer for her inactions, those questions (both action and inaction) are going to be critical in a trial for EG, and I can't see how she can possibly have good answers to them.