Those skills were part of the course curriculum that I designed which was approved by both the attorney who was a diver and the insurer for the agency. Our corporate attorney had learned to dive back in the day and was familiar with those skills. When I first learned to dive, tank valve breathing was part of the course so the correct technique was taught to open water divers. I wanted it included in the solo program because I saw the solo program as a way of teaching old-fashioned open water program skills that are being forgotten. As you and I know, skills aren't just procedural, but some skills are confidence-builders even after technology provides a better option. As far as BC breathing goes, the skill was taught with the low pressure inflator by holding both buttons simultaneously. We didn't use the bladder as a gas supply so the amount of time spent training and the amount of air that would come from the bag rather than the LP inflator probably made that skill no riskier than orally inflating a BC. Keep in mind students often accidentally inhale air escaping from the bladder during oral inflation training - which can be fatal in itself, at least for one British diver. According to Undercurrent that one case was the only fatality ever reported.
