Winfrey’s report was made at 10:28, the autopsy started at 7:00. Winfrey, the Deputy Coroner, was reporting the results of the autopsy. Any additional information to support CA would come from the forensic lab results which were not received by the lab until dec. 20. They changed the cause of death on dec. 13 based on no new information. Plus lab results can’t prove CA unless it is genetic.
You don't know that. We have three choices:
1. Winfrey's incident report was made before even the preliminary autopsy results were in and reflects the assumption that she drowned, given the fact that they found her floating in the ocean.
2. Winfrey made a mistake in that report, and the Coroner's Inquest form he signed later had the accurate information.
3. Harle, the ME, told Winfrey that the autopsy showed death by drowning, but at some point between 10:28 and whenever the Coroner's Inquest form was filled out, party or parties unknown pressured both men to change their story. Because, presumably, finding that she'd drowned during the hour she spent in the ocean would raise more suspicions than finding that she died of a heart problem.
The article writer has no reason to choose #3 except for being already committed to the conspiracy-murder narrative.