I am not familiar with the original story, but from the response (source: Srugim)it seems, briefly, that Kiryat Arba has a public pool that until now has only been open for gender-separate swimming hours. A group of residents, I dont know how large or small, has requested to also have gender-mixed hours. I guess the township said no and the group has petitioned the Supreme Court to require the township to provide residents with the option of some hours of gender-mixed swimming.

Other residents complained about this and sent a letter to Chief Rabbi Yitzchak Yosef asking him to intervene.

To that end, Rabbi Yosef sent a letter to the head of the township, Malachi Levenger, instructing him and all God-fearing residents to do whatever in their power to prevent this breach, considering how halachically problematic mixed swimming is.

That is all fine and dandy. Everyone is entitled to their opinions, halachically-based or not. If there is a significant sized group of residents that want to be serviced by their local public pool with mixed swimming hours, the township should provide for that - just like in a city with mixed swimming and a sizable population requesting separate swimming hours should also be accommodated.

The more interesting part of Rav Yosef's intervention is his reference to the city founders. Rav Yosef said that this would defile the holiness of Kiryat Arba that was founded by God fearing people to whom tradition was very dear and such a serious breach would hurt their ability to protect the character of the town, as most of the residents want it to be protected.

That's all nice and dandy but I am not sure what the relevance is. What difference does it make what the founders wanted? The character of cities change all the time, as residents move out and others move in with different beliefs and ideals. If Haredim move into a secular city, should they not change the character of the city because it goes against what the founders wanted, and what most of the residents want? Should they not install a generator, a mehadrin eruv, request separate swimming hours and build appropriate shuls and schools - because it isnt what the founders wanted and most residents dont want it either? Obviously not. Rav Yitzchak Yosef would definitely not advocate that religious residents of many cities not demand religious services, or more chumra-style behavior, just because it goes against what the founders of the city wanted. It doesn't work the other way either. Cities change their character over time. Public services need to be offered by the city administration equally or fairly among residents, and if enough want a service and it is financially and practically viable, they have an obligation to provide it.