Boyfriend said he would kick his daughter out for being a slut… Red flag?

My dad is verbally and emotionally abusive. Today he was digging into my mom and sister (14) and told my mom that she was teaching my little sister how to be a slut. All because she wanted to take a walk after they argued. I was listening to my sister talk and ended up late to plans with my boyfriend. I texted my boyfriend and said some crazy shit went down. When I saw him, he asked what happened. I told him about how my dad called my sister a slut. He said “well is she?” I was really thrown off and was like “she’s 14?” And he goes “so? She can still be a slut”. And was saying how if his daughter was a “slut”, he’d tell her and even kick her out and said she “was for the streets”.

Just feel like that’s abusive to tell your kid they’re a slut and kick them out because of their sex life. You’re supposed to love them unconditionally