The occasions when it would be necessary to refer to the "gender" of a human being or any other mammal, are vanishingly rare. Like all mammals, we actually possess not gender but SEX, of which there are two (1) male, which has a SRY (sexual region Y) genetic sequence (usually located on a Y chromosome) and produces sperm, and (2) female, which lacks SRY and produces ova.
Deliberate self-mutilation, surgical or otherwise, doesn't change your sex, but it is a symptom of major psychopathology.
Allowing the alteration of legal documents to record a surgical mutilation (or a regimen of hormonal confusion) as a sex change is a fraud and a falsification of the public record.
Thank you for knowing that gender is not the same as sex. I sat through sociology classes in college where the liberal professor would use ‘gender’ in place of ‘sex’.