Earlier quoted context omitted.
The only problem for GitHub now is finding a way to attract talent. If your best response to "You have a hostile work environment." is "We don't have a provably illegal hostile work environment." then that doesn't inspire great confidence when evaluating it as a place to work.
If you want to know if GitHub is a hostile work environment according to women who work there, take a poll of current and past female employees, including Horvath. I did. So far it's working out in GitHub's favour. But maybe I missed something, so do your own research.
I would think, however, that any sort of reasonable minority calling it a "hostile work environment" would indicate a problem.