Why must cooked TCS Foods such as steamed vegetables and fried chicken be kept hot until served?

To prevent the growth of bacteria. TCS (time/temperature control for safety) foods are any food that requires time and temperature control to keep them from being contaminated with harmful bacteria. Cooking food kills most bacteria, but some bacteria can survive and multiply quickly if the food is not kept hot enough. Cooked TCS foods must be kept at 140 degrees Fahrenheit or above to prevent bacteria from growing.