If anything, JC's methods reflect the "golden years" of Atlantic wreck diving, in the early 90s. At that time, technical training was much less organized than it is today, with more informal mentoring and with less concern about form, trim and the agency-driven certification hierarchy that we now have.
Times change. . . . Once they’re out of the class if they want to kneel, then it’s on them.
Better the other way around: Come to his course trained the way wreck divers are today, by-the-book, no kneeling, non-silting trim/propulsion nailed down cold, etc., and THEN learn from the master some techniques that may be rooted in the '90s but could still be useful today to add to your quiver.