There is no guarantee that lawsuits would be resolved as you think they should be. Liberal politics play too big of a role in the courts today.
You cannot practice without malpractice insurance. Defending these cases will be costly, and most likely malpractice carriers will not cover physicians who do this. Even big hospital systems who self insure will come to realize this is a risky practice, and hormonal therapy is not a big money maker.
A jury trial will not be sympathetic to the doctor. The majority of people in this country do not believe in this trans issue. It will be very hard to get a jury pool sympathetic to the doctor.