FYI, most states have broad exceptions to parental consent for medical treatment of minors. Most of those exceptions have to do with treatment for psychological, sexual or substance use issues. In those cases, the minor can provide their own legal consent to treatment, and I note from the original article that the age of legal consent in Oregon for medical treatment is 15. So in Oregon, a minor over the age of 15 can apparently consent to any medical treatment.
The sex-change operation is a headline grabber, but of course, finding a surgeon who would think that someone of that age is an appropriate candidate would not be easy. You would definitely want to have the patient evaluated by psychiatry and undergo a period of living the self-identified gender first, before contemplating surgery. I know that the medical literature on this has changed in recent years, and surgery is by no means a guarantee that you will end up with a satisfied patient at the end. I think the enthusiasm for gender-reassignment surgery amongst surgeons has really dropped.