Would they check for *that* kind of abuse? I'm sure they would check the skin and bones for bruising and breakage, but would a child's drowning bring on a check for molestation? If they found fluid in her lungs, no significant bruising, no broken bones, no suspicious medical history, and the family's stories matched and didn't seem to conflict with the evidence...would they automatically check for sexual abuse if every other sign pointed to accidental drowning?
If the child is hidden, sure they can't check for child abuse, but they sure can check for what family members might have had something to do with the disappearance. If GA feared ICA reporting his supposed abuse, wouldn't he think ICA would report it if the police came around checking on Caylee's whereabouts? He would have to know that Cindy, totally out of the loop and desperately wondering what happened to her grandchild, would eventually do something to trigger an investigation. And if he told ICA to get out of the house and go into hiding, he would have no way to know whether or not she might go to the police.
ETA: I'm kind of enjoying hashing this out and all of us trying to counter anything the DT might try to claim.