How would men coupling with male angels bring back the Nephilim?
It wouldn’t. But it was an evil alliance that basically was trying to overthrow God’s order. The term Gibborim is also used in Genesis 6 and with Nimrod. Nimrod began to be a Gibborim, so speculation only, there was something occult going on that such unions fostered.If the men coupled with the male angels then it was spiritual treason on top of all of Sodom’s other sins.