The story of the men of Gibeah closely mirrors the story of Sodom and Gomorrah and the consequences of violating the hospitality laws of the time.
The relevant part of this story begins:
vs. 15 - Consequently they turned aside there to go in to stay overnight in Gib′e·ah. And they proceeded to go in and sit down in the public square of the city, and there was nobody taking them on into the house to stay overnight.
Caring for strangers was supposed to be the cultural norm.
vs. 22 - ...the men of the city... surrounded the house... and they kept saying to the... the owner of the house: “Bring out the man that came into your house, that we may have intercourse with him.”
The townsmen were out to harm the visitor, the outsider - in violation of hospitality laws. This was common practice to show dominance, intimidate, and instill fear.
vs. 23 - At that the owner of the house went on out to them and said to them: “No, my brothers, do not do anything wrong, please, since this man has come into my house.
The owner took his responsibility as host seriously.
vs. 24 - Here are my virgin daughter and his concubine. Let me bring them out, please, and you rape them
Given the diminished value of women (disgusting - another topic), the owner offered two women in place of his guest.
vs. 25 - And the men did not want to listen to him. Hence the man took hold of his concubine and brought her forth to them outside; and they began to have intercourse with her, and kept on abusing her all night long until the morning
The men of Gibea didn't want the owner's daughter as she would not have served the purpose of the attack. They instead took the concubine, an outsider, and raped her.
This is the exact same scenario we read about in the account of Sodom & Gomorrah where Lot's daughters were offered and rejected because they did not serve the purpose of the attack. They were not outsiders. They were not considered a threat. An attack on them would not have served the purpose of the townsmen's goal to show dominance, intimidate, and instill fear.
“The cry of complaint about Sod′om and Go·mor′rah, yes, it is loud, and their sin, yes, it is very heavy." - Genesis 18:20
Sodom & Gomorrah, like the town of Gibeah was punished for the horrendous way they treated people.
Look! This is what proved to be the error of Sod′om your sister: Pride, sufficiency of bread and the carefreeness of keeping undisturbed were what happened to belong to her and her dependent towns, and the hand of the afflicted one and the poor one she did not strengthen. 50 And they continued to be haughty and to carry on a detestable thing before me, and I finally removed them, just as I saw [fit]. - Ezekiel 16:49, 50