Is this all about modesty? Are you sure? I would think that a pair of jeans, a blouse with long sleeves, and a small scarf would just about be the same as, a muslim sanctioned as modest enough to swim in, a brukini. And this is a far cry from a walking coffin they call a burka.
No, I'm not sure at all. That's not for me to be sure about.
I'm not a muslim or a woman. So therefore I can't decide for myself what is modest dress for a muslim woman according to my own interpretation to my own religion.
My religion as I understand it modest dress for women requires them to wear skirts. Some go further and say that they have to be ankle length, some say past the knee. I've been to Apostolic churches where they'd freak out if a woman wasn't wearing a head covering in church. I've been in others where the women could wear pants and not have their heads covered. My mom would always wear a ankle-length dress and a head covering visiting other churches just in case.
Back to the topic though, it's a personal decision. One that government has no business getting into "it's a security risk", just like they have no business getting into the business of a Koran burning pastor because of the "security risk". I think there's a serious question about the role of government here.