QuietStorm
Ashes, ashes, we all fall down
No, it is just that you don't understand the difference between cause and manner and what the ME is legally allowed to declare. It might be helpful if you go back and actually watch the clip of Dr. G., then read the autopsy report and her synopsis.
I think you'd be clear on her reasoning. You are welcome to disagree with her findings of course, but the picture might be more clear for you.
Text below is from Wikipedia, but it's the easiest to understand. The manner of death is DIFFERENT than cause of death. If a person dies from a heart attack, the MANNER of death would be natural and the cause of death would be something like myocardial infarction. If a person commits suicide the manner of death is suicide and the cause something like asphixiation. Either manner of death or cause of death can be UNDETERMINED. Manner = how did a person die and cause = what made a person die. (A cause of death can also be due to another factor, such as the cause of death being acute renal failure, due to or as a consequence of diabetes mellitis.) In Caylee's case, Dr. G ruled that the manner of her death was homicide, but the cause (how the homicide was accomplished), could not be determined.
Forensic autopsy
A forensic autopsy is used to determine the cause of death. Forensic science involves the application of the sciences to answer questions of interest to the legal system. In United States law, deaths are placed in one of five manners:
Natural
Accident
Homicide
Suicide
Undetermined