My late father, a graduate of Colgate University (WW2 GI Bill) in NY said this. Colgate was still a men’s school when he went there in the 40s. He gave to the alumni association for many years. When it went coed, he stopped. He said that men and women should be able to go to a single sex school if they want to.
I’m MUCH younger than your father, but he was correct and a VERY intelligent man.