One person should not have been able to reverse the decision that was made by a collective leadership vote. The fact that was allowed to happen is a failure of governance.
One of the people who left was the one who initially nominated ThePHD for the keynote. To have your nomination approved by a vote and then unilaterally overturned by someone working through backchannels would make me angry, too. If I was volunteering a bunch of time to a project that did that to me I might consider stepping down over it.