You are grasping at straws. I would be interested in any evidence you have for the claim that the air would be poisoned by floating corpses. According to
this paper, a 60kg human would have to ingest 10.8 g of pure putrecine every day for there to be a significant toxic effect. Is that your only way to explain away the fact that fishing and collecting rainwater are perfectly viable ways to survive for extended periods at sea? As far as I know, rotting meat doesn't make rain water unpotable. I await your evidence to the contrary. And if toxic corpse air were a real problem, it would have been just as fatal for Noah. Unless the Ark was airtight, which would be equally fatal eventually. And if anything such a bounty of flesh in the water would attract even more fish for survivors (Poon Lim caught sharks with a nail).
Poon Lim had "several tins of biscuits, a forty litre jug of water, some chocolate, a bag of sugar lumps". Not exactly an enormous supply. Are you really suggesting that nowhere in the world was there a ship with at least that much food loaded? Absurd. And again, he survived on a mere eight foot raft; people would be much better off with access to proper boats with supplies and proper fishing gear. Plus in a real ship you could sail away from corpse-clotted areas if that were really an issue. And if you wish to suggest that the entire surface of the water was clogged with corpses, you are in trouble because there is no more evidence for than than there is for the catastrophic Flood commonly imagined.
Correct. But that's why you're having so much trouble with this. You know there's no evidence for the Flood as traditionally envisioned, but the gradual Flood you describe makes near total annihilation of the global population absurdly unlikely. As Sarah says, why not just state that God made sure everyone drowned?