"For which particular sin, among other sins, was it that He actually destroyed a whole city?"
There are other instances of God laying waste to entire populations in the Old Testament. Off the top of my head there was Saul and the Amalekites. ISamuel:15
Aye, but those were through human intermediaries, not angels. And in those cases as well, the destruction was for the evil behaviour of those populations.
So by your logic, homosexuality is just one of the big No-No's--it is still not rendered acceptable.
Thanks for playing!