I might be wrong but isn't that a faulty argument. That's the same as saying that you pay tax in the US(or any other counter) and you therefore condone of all the behavior of said country? Or saying that if you use any Google product you promote corporate monopoly?
There's quite a way from paying for a service such as Github to promoting misogyny.
* 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.