The complaint about a New York City municipal pool allowing "female-only" hours for Hasidic Jewish women to swim freely without any men present is a justified one. The allowance of "female-only hours" for these women violates the separation of church and state. Government should not interfere with religious practice, but when the municipal pool provides accommodations for religious women, they are doing exactly that.
Fitness centres and pools make a number of accommodations for different groups of people. How is this accommodation any different from one where only children are allowed at the pool for lessons? Or when the pool is restricted to lane swimming only? It does have a religious component to it but that seems inconsequential. I think the real issue here is that the accommodation is for female-only - we live in a man's world and I believe if the tables were turned (i.e. there were male-only hours) there would be less, if any, complaints.
I think the New York City municipal pool should respect the wishes of Hasidic Jewish women so they can swim with no men present during certain hours. However I think that city should make all religious groups have equal access to have their beliefs protected and be awarded the same respect.
My feeling is that the public New York City pool is not committing a violation by providing hours where only females are allowed to swim. There are countless numbers of institutions and clubs that limit their membership by sex, age, etc. There are most likely many other females enjoying that swim time for their own individual reasons which make them inhibited in bathing suits in the presence of men.