I don't believe the state is trying to withhold evidence, they are only trying to be certain that these traumatic, and probably vivid photos of poor Caylee don't end up on the internet and on the cover of the grocery store tabloids!
As far as your last paragraph, I wouldn't have any problem at all with the prosecution wanting to be sure that my baby's photos of skeletal remains didn't end up public! It is blatantly apparent to me that they only want the ME's photos and findings to try to shoot holes in them as was stated by another poster. The defense doesn't have a case all they can try to do is get KC off on some technicality - so they are looking for some mistake somewhere - anywhere to help their case. While they are at it, they can make some $$!
If the prosecution just wants reassurance that the photos won't be sold, why is JB objecting? UNLESS HE (or someone) WANTS THEM SOLD FOR $$$!
This trial is going to be laughable I'm sure!