Even if she doesn't get a direct payment per copy sold, which I'm not sure I believe considering you know her negotiating power, there are still benefits for her. Increasing the brand increases future payments. Increases her bargaining power later on. And I'm sure allows her more creative control which means that any trans inclusion would probably be nullified in future projects.
Maybe it's a good game, but at a certain point you got to nut up or shut up. Are you going to take a stand and boycott something or not? Yeah you miss out on things with your boycott, that's the point. If you're not willing to sacrifice at all, and we're talking a very minimal sacrifice here aren't we, then what are you even doing?
Though why we are even talking about paying for it I don't quite understand. There's always other ways.