I'm wondering why it is necessary for an agency to try and control what an instructor does during the times when he/she is not acting as a representative of that agency... I can't think of any reason why this should be the case... does that have something to do with liability?
why do think they are not a representative of that agency at all times? They are endorsed by the agency to represent them, whether they are officially teaching for that agency or not at a specific time has no bearing on who they represent. For example, let's pick on Jim Wyatt for a little bit, he has thick skin. He is currently training director for the CDS, but also is very high up in the rankings for PADI. He is not able to conduct any PADI training without having to think about the consequences for the CDS, and vice versa.
I.e. every time Jim teaches a CDS cavern class he is at risk of violating PADI's training standards because students are allowed to use doubles/sidemount and he has the ability to go 100ft deep and 200ft of total penetration. PADI limits to 70/130. He is still a course director for PADI and a representative of their Tec-Rec program, but he is also TD for the CDS. He can't worry about violating those types of standards for PADI when he is teaching a CDS course. PADI also forbids air sharing drills in the overhead which I don't understand, but it's the rules, I don't make them. Now, because this is so minor, and he is well within the limits of the agency he is teaching for, he is at little real risk. PADI doesn't have a full cave program and their cavern program is mainly for MX recreational "caverns" and other types of non-cave cavern diving, lava tubes, coral caverns etc from what I understand. Their limits are based purely on recreational cavern diving with no intent of moving into full-cave from what I understand, so their limits make sense. CDS Cavern is more set up as a stepping stone to full cave, different courses, different requirements, same name. Very blurry line.
Now, Jim is also an instructor with IANTD, TDI, and I'm sure some others. Where the lines start getting less blurry is when you are conducting classes that can actually be counted as multiple agencies and when you blatantly violate standards and are doing what is deemed by the agency to be putting students lives at risk. This becomes cause for concern when you are teaching for multiple agencies a course that is designed for the same end goal, but they have very different standards. One agency may decide that violating those standards is now an issue where you risk damaging the cave permanently and are potentially endangering students, another may not. In that case, you should go to the lowest common denominator and not try to play the game of "oh well I wasn't teaching for agency X at the time, so I can just go and violate their standards at will". If you disagree with an agencies standards that much that you are willing to blatantly violate them, you shouldn't teach for that agency any more. Find one you agree with. That is why you don't see any of the GUE cave instructors on the CDS list, they don't match. You see cross agency with CDS/NACD/IANTD because their base standards are pretty much the same for the basic cave progression so they can go back and forth or teach for all three at the same time and it's OK.
These instructors are put in a tough position as far as what agencies they want to support and teach for, but if you don't agree with one agencies standards and are willing to violate them, you probably shouldn't be active with them anymore.
Frank, to your point. If I was PADI, yes I would have asked you to either stop teaching, or request that you drop active PADI membership because you weren't abiding by the rules that you had been asked to follow. You should have gone to SDI full time if that was your case and while you would have left in good standing, no refunds should have been given unless it was partial membership fees for the year. There is a very well known instructor that was asked to help develop a program for GUE and he has declined because he was asked to stop diving solo in the caves and he won't. For some of the diving he does, solo diving is the safest way to conduct these dives and because GUE is unable to accept that, they aren't progressing with that course of action. It is a shame for GUE, but they are sticking to their guns. If the agencies had more hard and fast rules like that and enforced them, there would be a lot less of a problem and we wouldn't be having this multi-agency discussion. If the agencies want to play nice together, then have forums where they discuss their current and proposed standards, and agree on them. If you don't agree, don't work with that agency. Pretty simple.