No, you are absolutely correct that you are not threatening. However, saying that is one thing that people will use to prop up their prejudice.
There have been studies of brain scans that particularly suggest that there are certain areas of the brain that are quite similar between those AFAB and trans women. In turn, that suggests that whatever happens occurs in utero and not after birth. Unfortunately the researchers didn’t have the funds to have a larger sample size so the results are considered to be inconclusive at present.
On a non-LGBT forum I stated this to someone and they continued to say: “It’s a choice!”. That’s the thing about belief. Logic and evidence are not needed and note that I say that as a Christian and someone who has held church offices in 2 of the 4 cities where I have lived.
Also, I appreciate the compliment!