If I understood the logic of your sodium system example, I think the point was that it would have been inappropriate to fully automate the control process and eliminate human oversight. There would always need to be a person overseeing the process and responding to information supplied by the control system. I completely agree with that concept. In spite of claims made by some regarding the state of artificial intelligence, software development has not reached the point where programs can be substituted completely for human oversight in systems where failure results in the serious consequences that you describe.