Why would you be worried about making it personal? I have no grudge against you; and take no offense. If I'm offended by what an anonymous person who probably will never meet me writes online, I need to talk to someone about that...
After a three day course a diver will have nascent skills, and a c-card.
So??? Divers are not required to stay under the wing of a mother hen instructor. Your OW card means you have the skills to dive. Now, go forth and gain experience.
Three days of OW diving should be sufficient to demonstrate the skills he has learned. If, after three days in the ocean, he can’t perform the repertoire of OW skills, there is another issue at hand; one that the instructor would have to diagnose and correct (if possible).
I have had enough training to reflect on what I do not know
I disagree. You know your limits because of who you are. You have the good judgment and common sense to know what you don’t know. That comes from who you are, not your training. Another person could go through the exact same training, display the same level of skill, and believe themselves ready for something they are not.
Diving is mostly about judgment and common sense. After nearly 14 years in the military, I can tell you for a FACT that there is no school, course, program, or agency that can teach good judgment. That comes with experience only. Likewise; there is no school, course, program, or agency that can teach common sense. He either has it...or does not. If he doesn't; it doesn't matter how good the instruction is; he will take risks. If he does have it, and I believe he does; he will avoid these risks.
The guy in your example is NOT a result of poor training. It is a result of a combination of bad judgment (not coming up when he knew he should, and breaking other rules), zero common sense (not watching his air), pride ("I know what I'm doing...and I don't need a refresher), and poor memory (forgetting skills like gear set up). Do you really think there's an instructor that NEVER taught him to set up a unit? Or didn't teach him to check his air?
Or was it the fault of this diver? At some point the individual has to take responsibility for their action. That point is when you accept that c-card. You become responsible for your diving; not your instructor, not your buddy, not the agency...YOU.
So no, he won't come out of the course proficient at the skills, ready to learn deep technical cave diving. You weren't that good when you took your c-card; neither was I. But we learned through experience. I believe that he will too, and develop that proficiency, as he gains experience.
Let the instructor judge when his skills meet the standard (which will be adequate, but in need of refining to reach proficiency- same as we were when we got our OW cards). Then, like every other diver, he is on his own to stay within the limits of his training, and dive responsibly.