> If Github was truly hostile towards women, why would they support the Ada Initiative in the first place?

It's never that simple. Almost everyone says they want more women in tech. But few take steps to actively promote that -- by increasing hiring of women, by fighting misogynistic elements of company culture, etc. Misogynistic company cultures are far more likely to arise through unconscious propagation of stereotypes and behaviors than from misogynistic leadership.

The Ada Initiative isn't trying to call Github misogynistic. It's just saying they haven't done a very good job of living up to their principles.