I ecourage you to review Genesis 22:7,8.
Isaac spoke up and said to his father Abraham, "Father?" "Yes, my son?" Abraham replied. "The fire and wood are here," Isaac said, "but where is the lamb for the burnt offering?"
Abraham answered, "God himself will provide the lamb for the burnt offering, my son." And the two of them went on together.
God WILL provide, not God HAS provided. Abraham knew God was not evil and therefore God would not allow Isacc to be killed. Maybe he would resurect him. Maybe the knife wouldn't hurt Isacc. He had no idea how god would resolve the issue, but he knew he would be returning with Isacc.
Now lets translate this to the Aliens. They down from the sky in a spaceship, performed all sorts of wonders and miracles, and predicted the future with uncanny accuracy, and even helped me and my wife conceive when we thought it was impossible.
Then the aliens then tell you that they need your son, whom they helped to create, to continue to be able to communicate with you and the earth in general. From you experience with these beings you know they are moral beings. You know that even if your son isn't with you he will be well cared for.
What do you do now?
Now your second assessment... I think you are tripping over a few language and cultural issues. From the prior section we know that Soddom and Gramorrah were currently at war with their neighbors. Next, strangers (not aliens as for as you can tell) randomly show up. The people of Soddom decide they might be spies and since then as now rape is about the most humiliating things one human can do to another, it is beleived that homosexual rape was used extensivly during interrogations.
Next you are forgetting the two most dramatic cultural changes in human society since the transition fromhunter-gatherer to agriculture. Specifically slavery and Womens liberation. Up until about 100 years ago women were assumed to be the property of their husband or the male head of the family. With only a few exceptions women have been property.
In ancient Israel, daughters have no choice on who they marry or even relate to. The daughter is property.
So now the story, now translated to the modern day reads:
Similarly, if {a potential spy} was about to {undergo 'enhanced interrogation'} at my doorstep by an angry mob, I might be willing to try to fight the mob off and risk my life, {I might even try to pay them to go away by giving them my most valuable and treasured property.} Heck, I might even be able to understand it if to fend the mob off I had to offer *myself* up for a good raping.
On the far side of the 20th century, we have to be very carefull that we don't let the morality that modern technology allows to interfere with the morality that has served mankind for over 3000 years.