Steve,
Your additional information is very helpful and amswers many of my initial concerns. Unfortunately we only have the information we read and what we "read between the lines." That being said maybe i should explain why I would have been so iritated.
I take diving very seriously and personally. If we had planned a dive and both understood the plan my expectation would be for everyone to follow it, including the instructor. I would make the assumption that if the plan was broken it was because there was some problem. Especially with an instructor deviating. I don't like games as to me once below the surface everything is for real.
With that thought in mind, as the buddy of the offending diver I would be going into "rescue mode? (without putting myself in undue danger) If it was due to his inattentiveness he would get a butt chewing for placing me in that situation. On the other hand if it was me dropping too low my buddies' job just bacame "rescue my big butt." And as I said originally, there would be some serios discussion afterword (hopefully chewing my butt) if it was due to inattentiveness.
I understand your reasoning, and now your methodology. Still don't decessarily agree with the style but hey, that's why there are many methods. The biggest thing I see that DO I like is making sure the student has actually LEARNED. Something missing in far too many instructors today.