My dad oks a child molester

So back story my step sister married this guy and he looks like a straight up crack head. We accept him and he seems like he has turned his life around. I brought my step sister up from another state because she was alleging she was abused by her native Indian husband. She gets married and everything is good after a year or two he starts going on vacations by himself and leaves my sister with my dad.(she’s 52 and living with my dad because she claims she fractured her ankle while drinking and between jobs)one night my brother and I start googling our names to see what comes up and found that my step sisters husband is a child molester and never had a clue. My father has taken my step sister the child molester into his home an tried to help them out. While doing that the child molester has invited this 23 old female that calls him daddy into the house which my father agreed to. I have talked to him and told him that this can go all kind of wrong. He doesn’t listen. AITAH to tell them to get the fuck out or leave him to his own problems?