Fine, I just don’t understand why the need to communicate this concept.
I wonder if this might possibly be due to the difference in our experience as males and females. As an adolescent, I was often annoyed, not only by boys, but by older men as well, who wanted to grab, touch, squeeze, and generally invade my personal space. I found it awkward to have to always be saying, verbally, "Stop that, Don't do that," and demeaning to have to actually fend men away from myself physically.
It is most uncomfortable ands disrespectful to be made to feel as if one were a bowl full of grapes that had been left out on the counter for any fellow to reach for as he passed by.
I'd not have been willing to go the "burqa" route, but if I could have worn a ring that had a generally recognized meaning of "Not sexually available," I would certainly have done so.
I do not see how the simplest signal of sexual continence is seen as problematic. By some males, I notice.