Sulli's friend explained why they had to speak up.
The friend 'A', who had revealed that they were friends with Sulli for 15 years, had originally called out the family for not letting Sulli rest in peace. After Sulli's brother apologized, 'A' explained why they felt like they had to speak up. They said, "Sulli is gone, so we are also guilty. I was not going to do anything and we believed that their family was the same. But Sulli's brother used the fact that he was her brother to talk to her fans, and her mother said things that we knew were not true. I understand how I look if I say something about her family. If I'm willing to take that, I hope you realize that I'm not just guessing at what's going on through just a few rants that I heard from Sulli about her family."
Hopefully things will settle down.
I can respect where they're coming from with this. In the end, they probably feel guilt that they didn't or possibly weren't able to do more for her now that she's gone. In a way, since she was used by so many people, it seems like this is the one thing they can do to help her since she cannot defend herself. Her family is using her death as a way to get one last bit out of her before her name falls into obscurity, including disgusting acts like exposing her private diary entries. I don't believe her friends have anything to gain from this so there shouldn't be an ulterior motive. They just want to defend her from her family using her in death like they did when she was alive.