Jammer Six, I get the distinct impression that you are a range shooting only instructor, and not a self-defense instructor. Most of your "safety" issues are in keeping with NRA RO/SO rules for static ranges; your emphasis seems to be on beginner's marksmanship and firearm safety. Those aren't bad things, by any means, but your focus appears to be limited to those things.
I don't know any reputable self-defense instructors who belittle people for answering the door, armed. In fact, those whom I know actually recommend it - and/or they recommend not opening the door to people they don't know.