Apusutayid -“Touro College is separate by design,because its what halacha wants, not because “that’s what the customers want”.”
Your story might be true that you heard, but it doesn’t mean that’s the reason. Touro made a school in Flatbush to cater to frum Jews, not because they held you can’t have a coed school, because they have coed schools. Once you have a separate school with mostly frum Jews, they weren’t going to change it to coed. There is no such halacha saying you can’t go to coed schools, that’s something you made up.