The goal is to explain that it is not as simple as XX or XY, not to say trans and intersex people face the same challenges.
To say that gender issues are piggybacking on homosexual issues is revisionism, full stop.
Trans people have spanned history, and much like people who experience same-sex attraction have experienced a variety of acceptance and rejection based on the culture at the time.
In what way is this piggy backing? In addition, as far as western contexts pre-GLBT, both transgender and same sex attracted people have been related since pre-nazi Germany and both were persecuted by the Nazis (to be clear, this is not an invitation to invoke Godwin's Law, nor me comparing you to a Nazi. It's just an example of a case where gay and trans individuals have been joined together).
E: Fixed spelling and expanded second paragraph.