I'm not sure how this is relevant to the point I've made, since I never said that we obtain a significant portion of electrolytes from water.
Ok, it's a little less intuitive to come at it from the opposite direction, but it's exactly the same argument: A liter of distilled water "sucks up" just 20mg more salt from the body than a liter of tap water. It "takes" that 20mg of salt from the 42 liters of water in the body.
The effect of the "physics based reasons" you are talking about is 20mg of salt from the entire body. Less than half a milligram of salt per liter of body fluids.
The normal range of serum sodium levels is about 15mg of salt per liter, or 30 times the difference caused by switching from tap to distilled.
In other words, this is an entirely theoretical risk that has zero practical effect on your neighbor's hyponatremia.