It's not like surgery, this treatment HAS to be done before puberty (i.e. 12)
Before puberty guys and girls are identical besides for the lack of a penis obviously. After pubery a whole bunch of crap happens to girls besides the obvious breasts. Their bone density changes, their lips plump up, they fat gets moved around, ther hemoglobin count changes, etc, etc.
Once a girl hits puberty she will always have a girl's body, even if she gets a "sex change". But if you coerce the body with testosterone at 12 she will become 100% male except for the penis. I also believe this article is referring to just blocking puberty, not administering the testosterone. Thus, all they are doing is preventing her from becoming "female". Therefore she can later on make the choice herself and go on whatever sex hormone she wants.
It actually sort of makes sense
