AITA for not fighting my parents on stopping my sister from being kicked out and telling my sister this is her own fault

I am 25, and my sister is 24. We both graduated from college and live at home. We both have jobs in the city, and it is easier to live at home and save money instead of spending 2000 a month on rent. Its that or live outside the city and deal with a 45 min drive of traffic. My parents’ house is right outside the city, and it’s a 10-min drive.

My parents literally have one main rule: no one is allowed to stay over without their permission. This is due to my oldest brother ex hookup. She robbed the house blind and caused a small fire. Everyone was fine, and after that, it was no longer bringing anyone to sleep over without our parents’ approval. I don’t really care because I find it weird to have sex in my childhood bed, so I am not bringing people home.

My sister, on the other hand, hates this rule, and my parents and her agrue about it quite often. They tell her to get a hotel or go to the guy’s place if she wants to hook up with strangers.

Anyways my sister brought home a girl last night, and my parents found out. They found out because they saw her leave on the doorbell camera. My parents were pissed and gave her a month to move out. It was a loud argument

My sister wanted me to talk with them, and I told her no. I told her that she knew the rules and why they are in place. She was pissed, and we got into an argument. She accused me of being jealous of her and her looks.I told her that I don’t care.

It went on for a while and she is pissed I won’t defend her agaisnt our parents.