She completely misses the fact that most shame is internal; we feel ashamed when we know we are doing something wrong. Someone else cannot make me feel ashamed of something that I genuinely think is acceptable. If a jewish or muslim person tried to shame me for eating bacon, I would just laugh. It's their rules, not mine, so I don't feel anything.
Also the way that she says that shame is a tool used to try and make people "behave well" with respect to a social norm, but then also says that this is generally inappropriate to do. Because whenever I challenge social norms it's good, necessary in fact, but when JKR supports the idea that only women should be in the women's changing room, thats bad.
This is all just special pleading to validate her own desire to shame others, while rejecting shame for anything she disagrees with. In short, she loves shame she just hates that she can't make up her own rules and apply it solely to benefit herself.
Imagine being so incoherent that even a Guardian journalist can see it...