I think you are reading to much into it. In my culture, it's common to call your daughter "son" and you don't seem anyone calling those folks transphobic. Also sometimes people say or think "oh i feel like an old man" "oh i feel like a girl" etc... In this case i think it's just a self deprecating joke which i guess if it's written by a cis person it could be seen as disrespectful but gmmtv trans artists often make jokes on their own accord.