Agreed, this seems unreasonable. Should minors be allowed to access potent psychedelic drugs or body mutilation "on demand"? On the basis that they appear to "consent and advocate" for themselves. That's the parents job, and unfortunately many parents are "lost" in this regard.
To bring things OT, unless you introduce a child to the notion that they were "born in the wrong body", they wouldn't be inclined to consider –let alone believe– it. The result is girls as young as 14 getting a double-mastectomy instead of appropriate mental health support, and a long growing list of detransitioners.
Those kids who benefit from an awareness of the "god" notion tend to have a moral compass and the understanding that god put them in the right body.