Its a good reply to Emma, and proves that actions and trendy speeches do actually have consequences.
JKR probably did feel fairly maternal towards all her child stars that voiced and characterised the characters that she had created.
i wonder if she was also especially close to Emma, because she played Hermione? The intelligent and underappreciated Swot! Of the 3 main characters, i wonder if JKR on some level would have identified most with the female witches and seen something of herself in them? So the betrayal by Emma was worse than others?
And I also wonder whether, when JKR was being ''awkward' whilst Harry Potter was being filmed, insisting on things like a British cast and filming in Britain, and ultimate editorial rights over her work, whether she also was extra supportive and helpful towards the child stars the films used? JKR personally cast Luna Lovegood didnt she after getting fan letters? ( PS I dont think JKR was awkward, they were her books and she had every right to impose conditions about how they were made, but I dont think this would have made her that popular in some quarters!!)
Its so interesting that Tom Felton who supported JKR, is still being supported by her and part of the Hogwarts world ?