I'd be very interested to see the mechanism. I can't imagine any company had a "pay women less" policy that got revoked. So what happened? Are women being brought into management more? It seems possible that a single promotion by the CEO could have major follow-on effects there. Had there been a subconscious tendency to shut down ideas that had women's names on them? Did the company culture move away from 60 hour weeks now that the CEO wants to get home early, allowing women (who are generally less willing to do 60 hours) to thrive?

I'm assuming the study conductors were competent statisticians, so there's a real effect and it pretty-much has to be causality as indicated.