Still, a mature adult would have recommended someone for the next version of conference and if all points out your recommendation is being taken seriously you do your part and deliver your conference in the current version.
What would you propose those speakers do differently?
A follow up question: why do you say that would be more effective than what they did?
(And, I would ask you, is that something that still maintains their commitment to diversity, since they all mentioned that was more important than speaking opportunities?)
I always find in life that you get better traction when you approach people with a solution instead of just a problem.
So perhaps they could've said "Hey, I think it'd be good to increase speaker diversity, and I really recommend person X, she's amazing at Y, I could approach her and ask if you'd like?"
Instead of just yelling "There's not enough women!"
I hope other conference organizers take note and work to improve diversity while also actively avoiding speakers who pull stunts like this.