More than a year ago I also participated in group therapy, but there were no rules.
Everybody was accepted, but nothing had to stay within the group.
This was the reason why it was helpful, when someone felt bad, everybody listened, no judgements, no advice, no calculating what to do about it, and that gives a feeling of validation, because when one tries too hard to make one feel better it smells like something is not right about oneself. Of course nobody offended anybody, well that might have been the rule but since all participants were intelligent, nobody had to explicitly point it out.
Anyhow I left because it was too boring for me since the other partcipants had much greater problems than I had.
I don't want to talk you out of something, but this thread sounds like you have to focus on the group only, like as if this group was the only thing in life or even life itself, that is what I consider too radical.
It seems to me that this group might be something like "if you want to get better, you gotta stick with us or go to hell".
Again, I don't want to imply anything since I have no insight in what you are going to do, But if it is too strict don't take it too seriously (I mean the whole focus on the group, however I fear the rules have to be obeyed.)