I started learning BDSM (it was just S&M to us at the time) in the mid-60's. My mentor was an old biker that had been active since the mid-50's. I imagine you already know that a lot of what is considered Old Guard was derived from the post-war biker culture. To the best of my knowledge, his group was run based on similar protocols. Again we didn't have such names for things, just strict rules. Getting information was a slow cumbersome process, or at least it was for us. Honor, respect, keeping your word, code of silence, etc were absolutes. If the gay leather community ran theirs the same way we ran ours, then that mistress was essentially correct. Getting in was difficult, getting out was difficult. Given where I was geographically (deep south, not near a major city) we were pretty isolated and did not interact with any of the gay leather groups at the time. So I can't say for sure but it seems reasonable within the framework I knew back then.