That's a mostly a precaution for human beings. The Associated Press article states that Nature's Variety is expanding a recall and that "salmonella can cause serious and sometimes fatal infections, especially in young children, the elderly and those with weakened immune systems. Pets can also become ill if they consume the bacteria."
Healthy cats (and dogs) have a natural resistance to salmonella. Clinical disease can manifest when there is a compromise to their immune system through age, stress or disease. When the salmonella is isolated from the feces of these animals it poses a threat to the owners however.
"As you may know, Nature’s Variety now uses High Pressure Pasteurization on our Raw Frozen Diets as a unique process to kill pathogenic bacteria through high-pressure, water-based technology. Having incorporated this state-of-the-art technology on our Freeze Dried Raw products in late 2009, we were able to confidently implement the process universally on all Raw Frozen Diets after the February 11, 2010 recall in order to further enhance food safety. Nature’s Variety also utilizes a test and hold protocol to ensure that all High Pressure Pasteurized Raw Frozen Diets test negative for harmful bacteria before being released for sale." <<<< I think they do this mostly for the safety of pet owners
But like I said, cats and dogs have a very short, acidic digestive tract which is very resilient to bacteria. Humans, being omnivores, have a longer digestive tract than carnivores. This allows food to "linger" for 24 hours or even longer, giving bacteria and parasites time to infect them. Hence the recall.