Okay, I'm not much of a Prudie fan, but when I read this article, I don't see it saying women should marry inadequate men just to have a husband for their bastards.
You can solve the problem of unwed mothers one of two ways--make them wed mothers or ENCOURAGE THEM TO NOT BE MOTHERS AT ALL!!!!
Obviously, the cousin mentioned above is an example of a women who should not be a mother. She has significant emotional maturity and relationship issues. No, having her marry the jerk who would knock up such a problematic woman would not solve her problems. But her pattern of getting knocked up and then handing off her brats to this older couple isn't solving her problems either.
To my mind, a marriage is nothing more than a contract. "We now own everything jointly and will take care of each other and any children. To break this agreement will require a deliberate effort and we place the power to seperate our assets in the hands of the court." Anyone who isn't willing to make that kind of committment to another adult, either at the courthouse or at the altar, is not a person ready to be a parent and commit their lives to a child. Male or female.