That sounds like the kind of thing that should be studied and not just pronounced in an HN comment. Just to repeat: the linked article looked at exactly this measurement and found the opposite effect (health benefits from lower electrolyte concentrations), albeit at a different end of the concentration spectrum.

That doesn't mean that you're wrong about a bathtub curve effect at very high hydration levels, but it means you have more work to do here.

Mostly: I don't buy it. My gut says that you're wrong and that at all but the most unreasonable levels of water intake we're healthier being hydrated.