Robert Galbraith pretends to be a different gender in order to gain a political advantage and make money. Having absolutely no sense of empathy whatsoever, he assumes everyone else is like him. He assumes trans people are all pretending to be a different gender in order to gain a political advantage and make money. And the only political advantage you can get out of trans femininity (as opposed to trans masculinity) is the appropriation of feminist resources.
(I mean, you can also get great skin, beautiful flowing locks, and resistance to covid from trans femininity, but I don’t think Robert knows about those)