Perhaps it was dumb. Perhaps not. I made a judgement call that I'd be able to make more of a difference to the company culture by sending a blunt email to the senior management team than I would by joining the company's middle management where I'd have very little influence anyway.
My hope is that they will implement some changes based on a. concern about their public image, and b. evidence that they are losing qualified candidates as a result of their imbalance. It is often the case with companies like this that many people on the inside would like to see a change but lack the evidence and support necessary to gain widespread support for it.
If it doesn't work it doesn't work, and yes I am involved in other activities to promote gender equality (both men and women's equality), both inside and outside work.