This is not nice. We are allowing them to dictate to us and forcing us to adapt to their 'religious' rules. If they want to use the pool, fine, use it, and swim in your stupid abaya. What's next, letting them swear-in using the Koran? (Oops, that's right, they are fighting for that right in North Carolina!)
There is no hint of "dictation" or "force." You have a group that pays money to rent a pool. They are women who like an unusual degree of privacy. Not only are they not forcing themselves on anybody, they are consciously keeping out of everybody else's face.
Maybe if you took a few deep breaths?
" If they want to use the pool, fine, use it, and swim in your stupid abaya. "
Maybe it's two fold. Just think of their savings on laundry soap.