If you read the article and citations you would know that a “preliminary cause of death by drowning does not mean they have not determined what the cause of death was. It just means they are awaiting the lab results to see if there is something in the blood that would reveal extenuating circumstances. In the case of cardiac arrhythmia something found in the blood may change the cause of death. However, in the case of drowning, whatever is in the blood would not rule out drowning. It may add to it, like the citation said, for instance if a lot of barbiturates were found in her system they could say that the drugs caused her to pass out, which caused her to slip under and drown. But the drowning part would still be there.
The person you are debating is not interested in the truth. He will post something entirely untrue, and when called on it will split hairs, then split the split hairs, then dissemble, and if/when you finally nail him in a flat-out, undeniable lie [it isn’t easy; he’s as slithery as a sea jelly] he will pronounce it “irrelevant”.
Just so you know.