It is child abuse.
Poor girl, if she never does learn to become comfortable with her sex, her life will be very much diminished by her learned desire to be something she is not. Particularly when purity comes along to confuse her further. She will never know the joys of having children of her own if their misguided mindset drives her to remove the parts she needs.
On the other hand if she does come to accept and love being a girl, she will be embarrassed and weakened by the childhood experience. If it happens after she makes consequential choices with surgery or drugs, she will be crippled for life.
Children are not old enough to make important choices, they do not understand the world as it is or even themselves, They won’t until they have adult minds and maybe not even after that for some of us. It is the job of parents to protect children not simply from the world but most of all from themselves until they reach that age in which they can protect themselves. This is called parenting. Brad Pitt and Angelina are doing a very big disservice for the children they have taken into their care.
You are correct. Children are too young to make those kind of choices about their gender. Shame on the parents who push it.