I think it's quite possible for people to teach things about diving without going through an instructor course. People who have had good training themselves can turn around and pass that along -- if they truly mastered and understood the training that they got. They won't have, perhaps, quite the repertoire of incident avoidance and coping techniques that someone with instructional training has, but not all instructors get the same quality class or come away from their class with all the things that were in it.
However, I think that taking someone onto a complex and potentially lethal piece of new equipment with no advance education, and then leading them not into a simple and relatively short dive to test their comfort with the gear, but into a dive with an hour's deco obligation (which is enough that you can't blow it off and expect to come out whole) is irresponsible. This is the kind of thing you'd probably learn enough NOT to do, if you took formal rebreather instructor training. (Although, I think, most of us would be smart enough not to do it, anyway.)
When I did my "try dive" on a rebreather, I had been sitting in for a week on the above-water sessions, and the dive was to 15 feet, and I had my (non-instructor) buddy in the water doing NOTHING but monitoring me, and the whole thing had been cleared by HIS instructor, who was on the boat, and had worked with me in the past. I don't think that was unduly foolhardy. I think what the OP did was.
However, I think that taking someone onto a complex and potentially lethal piece of new equipment with no advance education, and then leading them not into a simple and relatively short dive to test their comfort with the gear, but into a dive with an hour's deco obligation (which is enough that you can't blow it off and expect to come out whole) is irresponsible. This is the kind of thing you'd probably learn enough NOT to do, if you took formal rebreather instructor training. (Although, I think, most of us would be smart enough not to do it, anyway.)
When I did my "try dive" on a rebreather, I had been sitting in for a week on the above-water sessions, and the dive was to 15 feet, and I had my (non-instructor) buddy in the water doing NOTHING but monitoring me, and the whole thing had been cleared by HIS instructor, who was on the boat, and had worked with me in the past. I don't think that was unduly foolhardy. I think what the OP did was.