> Why were they there? Because they were invited! The only rational response is to turn down such an invitation in the future.

The Ada Initiative recommends[1] responding thusly:

* Respond saying that you'd be honored, but the panel seems awfully heavy on the men, and can they find a qualified woman to join the panel? Here are some suggestions.

* Respond saying that you have taken a pledge not to participate in all-male panels from now on, but you'd be happy to join if a qualified woman is added.

* If you can't accept, suggest a qualified woman to take your place.

[1] http://geekfeminism.wikia.com/wiki/Allies_training#Scenario:...