I am not sure what your point is.
My point is why do you think it's so important to talk about one particular condition, gender dysphoria, but not the whole medical dictionary?
If he acknowledged all that was true, but insisted he knew he was a girl, would you accept his identity or not? Would you say "you are not a girl" and refuse to refer to him as such?
Yes, because he's not a girl. It doesn't help him to go along with any delusion he has that he is. He is not and can never be a girl because people can't change sex.
If he insisted he was a dog, would you take him to a vet when he got ill, feed him from a bowl on the floor and take him for walks on a lead? And go along with his 'identity' that he is really a dog? And tell him he can take medication and have surgery to make him into a dog, and that when he grows up he can give birth to puppies?
Everyone should be encouraged to live their lives in the way that they feel most comfortable (as long as it doesn't harm others). We should not be going along with the delusions of confused children. This really doesn't help them at all. I'll say it once more: people can't change sex. Pretending that they can is not helpful to anyone. Least of all to the children themselves.
Telling a child that they can change sex, or that they 'really are' the opposite sex is child abuse. It should be stopped, not encouraged.