I don't buy it.
He (allegedly) has gone through puberty, he has seen his male and female peers go through puberty. You learn the basics of puberty and sexual biology in school.
He knows how big of a deal it is, how fast and major the changes and growth can be.
Only someone who is genuinely retarded could think that you can just stop the process or get the hormones of the opposite sex without huge consequences.
And even if you don't get the chop, MTFs are short, squeaky eunuchs with a babydick and weird HRT boobs.