Was my husband's wrong to unfriend my sister

My sister called me upset saying she noticed she hasn't seen any post from my husband because he usually posts memes and went to search him up and he unfriended her. I asked my husband why and he said because her and her fiancè's posts are annoying and he unfriended both of them. My sister and her fiancè are on and off. He says one minute they're posting that they love each other the next she's making a post about how he did her dirty and he's making a post calling her a liar. He told me they switch up every few days. One minute they're fine and saying how they can't wait to marry each other and the next they're in a fight in the comments calling each other bitches and hoes and he said he's tired of seeing that on his timeline. He also said he doesn't really talk to my sister anyway and doesn't understand why she cares so much. I said she's his family now and we are there for each other. He says "I'll be there and she needs to be picked up again because he kicked her out the car because they were fighting. I don't want her bullshit on my timeline and at the end of the day it's my Facebook". Should he friend her back?

My sister isn't being emotionally abused. If anything they emotionally abuse each other but I'm still there for her. I did say why he didn't just unfollow but he said he unfriended and that's that.