Trans is an umbrella term that can be used to refer to anybody who does not identify with or express the gender they were assigned at birth (https://www.hrc.org/resources/sexual-orientation-and-gender-...). Having surgery and/or always presenting as a gender you weren't assigned at birth is not a prerequisite to being trans. "Transvestite" is a somewhat dated term that is considered offensive in some circles, though either way, a transvestite would by definition be "trans".
I wonder if that's an easily disproven talking point...
Wording has changed throughout history as has our understanding of gender and sexuality. While the specific word "transgender" may not have existed, it's still true that she lived as a woman at the time. At the very least, you can't argue that there's gender-nonconformity going on there. The fact that the Stonewall monument was targeted for removing references of "trans" should hint at why the author of the extension named it this way.
> it's still true that she lived as a woman at the time
That's an awfully sexist perspective, isn't it?
A man acting out some feminine stereotypes doesn't somehow become a woman by doing so.
Sure, but there's a clear difference between a man who dresses feminine sometimes but otherwise still prefers being referred to as a man and Marsha Johnson. She moved to a new town, changed her name, went by feminine pronouns, and pretty much exclusively dressed as a woman. That's what I meant by my comment, but thanks for giving me the benefit of the doubt.