in the Information Technology field? This might go some way to explain it.
Did Yahoo not think that women engineers would be present at this event? They make up roughly ten percent of engineers as a whole. Furthermore, did they think that there was some way that women attendees would be perfectly comfortable watching other women objectified on a stage?
It's not that I mind women being objectified for money -- the women involved are handsomely rewarded for their parts in this business deal. I do mind people in my field saying that they do everything they can to make women comfortable in our field, then turning around and saying that they don't understand why anyone would be offended by this.