I think that is most often true. However, there are risks to being outed if you are stealth and those risks could be more significant than the risks of being treated as the gender you present than as the gender you were assigned an birth.

The treatment of a broken bone is largely independent of the mix of sex hormones, presence or absence of sex-differentiated organs, or gender presentation now or at the moment of birth, but can still involve an ambulance ride and a hospital visit. I'd hope our medical system would be trans-safe enough that disclosure would be a strict positive, but I don't know that's the case, and I would defer to the patient's judgement about whether to disclose or not for whatever reasons (including but not limited to safety and comfort).