[Partisan Gunslinger]

Well, perhaps squeamishness is not the best way to characterize their motivations, but yes. That is the traditional interpretation, not an innovation.

If it is the traditional interpretation of Gen 6, can you show me a paper from medieval times discussing it, or up to 1800 or so?

[Boogieman]

Well, there is the Book of Enoch, which is at least as old as the Dead Sea Scrolls, so no later than the 1st Century AD. The Book of Jubilees also assumes the same interpretation, and is at least as old as Enoch.

Josephus ascribed to that interpretion in “Antiquities of the Jews”, ca AD 94. It was also the commonly expressed opinion of the early church fathers, recorded by the Anti-Nicene fathers, Justin Martyr, Irenaeus, Clement, and others. The interpretation was also recorded in the Jewish Midrash Targum Yerushalmi (pseudo-Jonathan), of uncertain date, but probably composed between 800-1300 AD.