I would tend to agree, except that bacon fat has salt in it, which can cause some problems if it is used to season younger pots and pans that don't already have a good seasoning coat built up. Palm shortening is excellent, and is one of the ingredients in Camp Chef's Cast Iron conditioner for much the same reason. Actually, I believe that heating the oil/grease to the scorch point, which is necessary to get a good seasoning coat, is a depolymerization process, as the heat is breaking down the material and "volatizing" off the lighter compounds, progessively leaving behind a residue that eventually becomes a carbonized solid. Blast may have better insight into the chemical decomposition process than I do. As far as the metal utensils go, I guess you can either scrub or scrape, whichever works best for you. I can and have used metal utensils in my cast iron, but I do not recommend it, nor should it be necessary. To each his own. If it works, then by all means, indulge.
Unless you let your pots get rusty, you will not increase the iron uptake from eating out of well seasoned cast iron. I try to keep my pots and pans seasoned so that an unpermissive barrier is maintained between the food and the metal surface.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)