>you'd expect a well-off socially accepted trans woman on HRT to live longer than a genetically identical cis man. She has an improved immune system due to lower testosterone...
I don't think this is a very factual conclusion. When it comes to the long term physical and mental outcomes of transgender hormonal therapy, we simply don't know. If we don't know the long term implications of infusing our bodies with synthetic hormones, then I would consider that to be a health risk.
While I fully support adult's decisions to put whatever chemicals they want to into their bodies, hormonal therapy seems like a health risk and is certainly, by any definition of the term, unnatural. I don't believe I am a bigot because of this opinion, either.