The protest isn't a defence of the Burkha, which is undoubtedly an unfortunate symbol of patriarchal Islam. It's a defence of the right to wear what one chooses to wear. Many islamic women have made the choice to follow this part of their religion. These are not necessarily women living under dogged oppression on a daily basis. In the same way some Catholic women will not use contraception. Both are examples of a deeply patriarchal religion dictating to women. One is more visible, one is potentially more physically harmful.
I have no evidence, but I sincerely doubt that fundamentalists will be on the beach in a Burkini. I'd guess that fundamentalists hate these women more than the French do.
Let's have a proper public debate, rather than an ill thought out ban.