This situation is very serious. Based on all the information we have so far, I'm not taking sides on either one of them, especially when I personally don't know them. I'm just an observer of their situation, but I will give my 2 cents. I'll stay neutral until both parties have been heard and given a proper investigation.
If the accusations were proven to be true, then it's best for Pledis and Seventeen to kick Mingyu out. Because if they didn't, the members' as well as the whole group's career will be ruined. He was old enough during that time to differentiate what's right from wrong. Let him face the consequences of his actions. I hope the victim gets a proper and genuine apology from Mingyu. I also hope that the victim gets a peace of mind after all of this. She has been through a lot, very courageous of her to speak up and share a very personal experience to a lot of people. Depression is no joke, especially what she has been through, she could have taken her own life.
If those accusations were proven to be false, then I hope Pledis would take legal actions. There are hundreds of innocent people being thrown into jail for years, getting their lives ruined, and/or even falling into depression because of being wrongly accused. Yes, you have been proven to be innocent in the end, but that kind of experience will be unforgettable. Especially from well-known people, that kind of scandal will most likely be brought up, again and again.
Life is unfair, so I'm really hoping that true justice will prevail in the end.