[user104658]

Evidence is strong that the only reason for reduced suicidality post-gender reassignment (with or without hormones) is catharsis. Suicidality tends to return within 5 years. The argument oft given is that this is because the person is still experiencing persecution and unacceptance -- but that's largely just because people don't understand what catharsis is and how it works, so they don't understand why someone would seem better/happier for years and then have their mental health decline again. It's literally just time and diminishing returns.