Don't confuse "food" with "meals". Food is any protein, fat or carbohydrate singularly or together that provides nourishment, period. Food doesn't have to be pot roast.
Sorry, you have a problem with my statement but it is actually factual. Older people definitely benefit from more bio-available protein especially very active people. Whey powder is nothing more than mechanically filtered and dried whey and not only does it help with muscle repair and development but with heart health, diabetes prevention and inflammation. People that use whey have more muscle and less body fat especially older people. It is probably the easiest protein to digest apart from hydrolyzed sources of protein.
Just think of it as a dairy food, which is what it is. There is nothing fancy or mysterious about it. The only possible side effect is gas.