Think of a copy of a painting that was painted by someone other than the original artist. If the forger's name is Williams and they copy a Picasso, we don't call it a Williams forgery. We call it a Picasso forgery to indicate what the copier was trying to imitate. The copier tries his best to make his painting look like the real thing, including insisting that it's made by the original artist by putting a copy of Picasso's name on it. But it's not, and no matter how good it is, there are always tells that give it away. It's a Picasso forgery, not an actual Picasso.

The transwoman is the same thing, except by and large far less talented or motivated. He paints himself up in the best imitation of a woman that he's capable of, all the while chanting that he's a 'woman'. But he's not. He's a forgery of a woman. Calling him a man in any but biological terms doesn't seem quite right either because he's not worthy of that word anymore. But neither is he worthy of calling a woman. He's a transwoman - a woman forgery, not an actual woman.

To that end, I think the word should be further normalized by people who oppose the Trans and used as often as possible as an insult. For example, Whoopi Goldberg is my favourite transwoman.