That study did not measure anyone's zinc status, it just assumed people were not zinc deficient based on the food supply.
"The estimate was based on the food balance sheets, the bioavailability of Zn in the food supply, the estimated physiological requirement of Zn in individuals, population demographics, and stunting observed in children."
I am not pushing it as a population level mitigation. But what if 50% of people could avoid covid if they fixed their zinc deficiency?
And you even admit "Nutrition may well play an important role for individuals based on their specific needs". So why are they not letting people get tested for nutritional deficiencies? What wold that even hurt?
And I agree that your aunt is an idiot and knows nothing about nutritional genomics.