And the first-born said unto the younger, Our father is old, and there is not a man in the earth to come in unto us after the manner of all the earth: (ASV)
And in the remaining verses, Lot's daughters make him drunk and have sex with him -- they committed incestuous rape. And we are told that the children they had are the legendary ancestors of the Ammonites and Moabites, thus imputing a disreputable origin to them.
I don't see the problem. People in the Bible aren't necessarily moral. I don't know of anyone who claims the Bible documents only the lives of moral people and only behavior approved by God. Furthermore, I don't see what the author of the Pro section is driving at. The daughters started families immorally. Unfortunately, it happens sometimes.
Edit this section to note miscellaneous facts.