There is one reason to clean a CI pot. To remove foo residuals where bacteria can grow.
There are basically no bacteria alive coming from the cooking process. Cooking in CI kills all bacteria.
Reason to remove residuals (and soap helps because of water tension and making fat mini drops soluble in water) is that if you leave food residuals they might get infected by bacteria and become a bacteria colture.
Here is something that most of the people don't take into consideration. If the infection of bacteria is not massive like just one bacteria grows on a piece of meat left on CI, and if that piece of meat is in a corner where there is some water closed, and that bacteria happens to be a common soil like a clostridium, that can become dangerous.
You might think that you can still cook because the cooking kills the bacteria and here is how you get poisoned, the clostridium colture, once gets into a stress (like raising temperature) produces toxines. How many people was poisoned thinking that boiling was sufficient, you kill the bacteria but you eat toxines. Same is for defrosted food, you put it back in the freezer and the bacteria emits toxines.
The reason why this never happens with concencious CI owners is that CI is dried and kept in non moistured places. But grills could be dangerous if left in moisture or wet without cleaning (soap or non soap).
The principle is that cleaning is to remove food residuals, but storing dryness is essential. To the point that having to choose, better a dry kept pan than a clean pan.
That is why meat that is not cleaned but kept into dry place is edible. Like prosciutto!
Honey is wet. But the sugar content is so high compared to the moisture, that it becomes a hypotonic solution and actually removes moisture from micro-organizms and kills them, hence its antiseptic properties.
Other "dry" food products, such as dry-cured salamies (hard salami, pepperoni, etc) are actualy not completely dry. But they have had beneficial bacterial cultures added to them that ingest sugars from the sausage mixture and excrete acids, along with the addition of a contolled amount of solium nitrates and or sodium nitrites that inhibit the growth of dangerous micro-organizms, renderes the sausage safe to eat without refrigeration.
The same is true of sourdough and cheese. The yeast in sourdough, and beneficial organizms in cheese release enough acids so as to make the food inhospitable to harmful abcterial cultures.
The above examples show that moisture does not automatically allow dangerous pathogens to grow in food. Of course moiture is one of the required elements needed to support bacterial growth and so moiture controll is a necessary part of food handling safety. But there is so much more.
Food particles on any surface can, under the right conditions, support dangerous bacteria. However, there are micro-critters that survive temperatures in excess of 900 degrees F. (think undersea volcanic vents), and the vacuum and extreme cold of space (think yeast spores), and the arid onditions of high desert (think brine shrimp). These are all extreme examples, but valid ones. Yes, we must take care to keep our cooking utensiles, and work surfaces clean. But CI is safe when cleaned with hot water and a stiff brush to remove the food particles. Soap isn't usually reauired, and note that I say usually.
On the flip side, a properly seasoned cast iron pan isn't damaged by the use of soap and hot water. Simply rub a little cooking oil or grease on the pan surface after drying with heat and the surface is ready to go. The fat will protect the metal against any corrosion. Just remember that the fat will go rancid if the pan is stored for a lengthy tiime and must be removed before cooking again. It must then be re-applied. You will know when the fat is rancid by the nasty odor. You can store seasnoed cast iron indefinitely after washing with soap and water if the pan is stored in a moisture proof plastic bag.
A little common sense, and some biology knowledge goes a long way toward successfully caring for and safely using you cast iron pans.
Seeeeeeya; Goodweed of the North