“The Chofetz Chaim and the Ribnitzer Rebbe, to take two recent examples that come to mind, married young never married women when they were in their old age.”
Joseph,
You’re mistaken, the Chofetz Chaim’s second wife was previously married, as it states in his will from 1926:
“The one who is the overseer of my business dealings is the son-in-law of my wife. His name is Harav Reb Hillel the son of Rav Moshe Zalman Ginzburg.”
I believe the Ribnitzer Rebbetzin had also been previously married.