Who is the "they" in this sentence? GUE the organization or divers who have taken GUE courses? (We dealt with the "members" issue earlier and clarified that membership is a separate thing from the training courses. And maybe that's why you put "members" in quotations.) I prefer to focus on us divers, not the agencies from which we received training. Focusing on GUE the organization rather than the divers who took GUE courses is looking for a bogeyman. Some divers are going to be judgmental and frown on others' ways of doing things, but I don't think this is exclusive to GUE-trained divers. For the most part, the GUE-trained divers I have been acquainted with don't seem overly concerned about what others who are not their dive buddies may do "on their own time."
Can you point to these "rules" about "on their own time"? There are definitely standards for how dives are conducted during courses, and the non-smoker thing is a prerequisite for taking a course, but outside of a course or a dive where your buddies want to adhere to GUE standards, I think some of the things that seem to concern you are more aspirational than "set." You could, if you so chose, do whatever you want outside of a course and outside of a dive where the buddy team agrees to adhere to GUE standards. Keep in mind there are many divers, even cave and tech, who received training from multiple agencies--some are even instructors for multiple agencies.
Any repercussions from doing something that goes against the grain of what GUE teaches are not likely to come from GUE the organization but rather from prospective dive buddies. If someone gets the impression you are an unsafe diver, then I can completely understand how they might decline to dive with you. If someone who has no interest in diving with you pipes up with criticism about how you dive, then they are a judgmental jerk.
By the way, does GUE have a standard that addreseses hunting? I've never heard that, though I could see the argument that hunting conflicts with GUE's promotion of marine life conservation.