I can see why an octogenarian w/ a persistent fever would be placed in the ICU. But why a liquid diet?

The real question you have to ask is exactly what do they mean by liquid diet. The lay public hears liquid diet and thinks his food is being blended. To me it means he is on a formula diet through a tube placed into his stomach, but more likely he was on that is called TPN which provides all nutritional requirements through the circulatory sister directly (IV), and whoever was Writing the article couldn't differentiate between enteral and parenteral feeding. Generally people in ICU are just to sick to eat and they need TPN to maintain their electrolyte balance' and not waste away. As for the people concerned about Choaking, liquids are thickened and eliminated as much as possible to avoid aspiration, but as there is no diagnisis of dysphagia I wouldn't think that aspiration is a manor concern.

They don't want to risk him choking when he is coughing. That is why he is on a liquid diet.

I can only imagine its because he's on oxygen...and having lung problems solid food can be aspirated into his lungs and cause complications...