Github promoted misogyny internally. You give them revenue, allowing them to continue to run their business. Ergo, you are promoting the misogyny Github promotes* internally.

* The burden of proof that Github doesn't promote misogyny is on Github.

EDIT: I personally use Github, but I cancelled my account after what happened. For new projects I use bitbucket. I actually feel bad when I'm using Github precisely because to a degree it means I'm promoting misogyny.