@ApostateEnglishman It wasn't me, but I Have Thoughts.
"Traditional marriage" and "family values" are IMHO code for "traditional gender roles". L/G couples really *are* a threat to traditional gender roles.
If the neighbourhood children should see (*horrors*!) a man ironing or cooking, or a woman fixing the water heater, then the neighbourhood children might get the idea that maybe traditional gender roles weren't that important.
I'm not as sure about why trans women make cis men go batshit crazy. (I don't really think they care about trans men.) My best theory is that conservative men think that being a man is OBVIOUSLY way better than being a woman, so the idea that a man would *choose* to leave the best gender breaks their brains.
Obviously, they think, being a woman is inferior to being a man, so *they must be doing it for nefarious reasons*. Like they are lying about wanting to be a woman, they just want to be able to leer at naked women in the locker rooms.
That's my best guess, anyway.