Ellenpolly, at first I thought you were right, but then I re-read what Bobert had written...a couple of times.

He's actually criticizing the professor for not 'knowing' you can get aids from malnutrition. You don't get colds from not wearing a hat in the winter, and you don't get infected with the HIV virus from being malnourished. A person might be more susceptible to the ravages of HIV if they're malnourished, but they won't GET it.