My comparison has absolutely nothing to do with any considerations of prior oppression.
But if you insist on taking that line..... I'd say that transgender people could lay a pretty fair claim to having been oppressed by the rest of society - by us - up to now. Woudn't you?
Note also that in my counterexample, I suggested that one subgroup (white girls/women) out of the whole set of people whom the civil rights legislation was not aimed at helping (that whole set therefore equalling all white people) ended up being placed at potentially increased danger as a direct consequence of that legislation.
Just as, wrt transgender legislation, I suggest that one subgroup (cisgender girls/women) out of the whole set of people whom the civil rights legislation was not aimed at helping (that whole set therefore equalling all cisgendered people) might end up being placed at potentially increased danger as a direct consequence of that legislation.
Each to his/her own, I guess.