As both an event organiser and a woman in tech and science, I agree – this is just not an acceptable excuse anymore. 

“His comment about being “happy with our process” doesn’t cut it in 2013. I’ve seen excuses from other criticised conference organisers, saying that they couldn’t find any female developers, or the ones they asked didn’t want to speak, or that their specific niche just doesn’t have that many female developers — I don’t think it’s good enough any more.”

http://www.threechords.org/blog/diversity-in-tech-still-an-issue-2013/