She simply defended the rights of trans people. She always has stuck up for people. If you knew her you would not call her anything but an outstanding and kind person.
It seems that Rosie Kay gave your daughter and other young people mentorship and a valuable opportunity to perform in a well-regarded piece of art, yet you think it's wholly appropriate to strip her of a source of income and her art on the say so of your daughter and her peers?
It's verifiable that JK Rowling is a remarkable philanthropist who has done a vast amount of good and has admirable compassion for others. Tell me, would you and your daughter acknowledge JKR as an outstanding and kind person? If not, why not?