None of them have said anything disrespectful or insulting. They’ve disagreed with her, which they are allowed to do, but they haven’t thrown insults or said anything disrespectful about her or her work.
That’s perfectly acceptable. People can voice their opinion. You’re saying he needs to show her loyalty because he got a job from a book she wrote. He doesn’t. No one needs to stay on side with anyone just because they got a job from them.
It is a ridiculous comment to make and I see it over and over on this site, “How dare he speak out against someone he owes his role as Harry to.” So what?
I disagree with him. I agree with JK Rowling. But her role as Harry Potter creator has absolutely nothing to do with who should be on her side.