Hogwash. Companies always say they will open an investigation. In the least, it buys a little time for the story to die down and the next big stories to hit the media cycle.
I admit, I do care about things more than most. My workgroup, and much of the company I work for migrated to github enterprise (and a lot in github public) about a year ago. These kinds of things sour opinion. There are differences between a single bad actor/incident and a systemic problem in a toxic workplace. We don't really know what this is, but it was clearly more than at least one person was willing to put up with.
It's bound to be difficult working in an environment where 4:5 of your peers are the other gender. I worked in a couple of workplaces when I was younger where I was the only male. It was rather eye opening and sometimes uncomfortable to say the least.
Also, people might forget about the issue in 6 months, but the bad taste in the mouth we have now will stay attached to the brand. The best move IMO would be to come 'clean' as soon as possible, and let the hype die down from there, provided they are OK with doing the right thing, whatever it might be.