No doubt it was a toxic set, everyone has said the show went on for 18 hours of production, with shooting ending on Saturday morning in some cases. A cast of several dozen twenty year olds shot in a night club also had discipline issues. This is why you don't make 23 episode long seasons anymore. Television production has a lot of human wreckage. If you look at Joss's record on, let's say, Firefly, which had a real budget, real actors, sufficient production staff and time to film this, nobody has a bad word to say about Joss. The real villain is the WB's production schedule.
Yeah, Michelle's an idiot. Look, she was very sick for the last few years of her life, and I don't wish to speak ill of the dead, but it eventually came out that Joss yelled at her, and hard for something. But, you would be excused for thinking he tried to rape her, because the way that she, or her people, more likely, revealed her story in an extremely sensationalistic way.
Gal Gadot isn't a good actress, and Justice League reshoots were supposed to be brutal. He probably did lose his temper with her. However, that doesn't get you blacklisted.
Re: Cordelia: I think the interview excerpts covered it, There's context involved. I mean, Charisma's son is far more important than some TV show she did thirty years ago, but it's pretty annoying for the people running that TV show.
Again, Joss burned his bridges with Disney, I suspect Warner blames him for the failure of Justice League, Batgirl and the Nevers. 20th Century Fox is gone. Zack Snyder's partisans hate him, and his own stans have abandoned him. If he's working uncredited or under a pseudonym, well, I'm not going to know that, but I suspect that part of the reason that WB hates him, is because they paid him quite a bit. So, no, I do not believe his crimes would merit an exile of this length, but I don't believe that anyone really wants to work with him, either.