I suspect there was no one single event. His mailing list rants have been known for a while, and the occasionally make it to the tops of sites like HN/Redit/etc

I suspect there was no one single event. His mailing list rants have been known for a while, and the occasionally make it to the tops of sites like HN/Redit/etc. I doubt it was less of a "Straw that broke the camel's back" and more of just a "We all know this was coming," thing. Or maybe it was? ... from the e-mail, it might have been words/things from maintainers, specifically around the meeting/conference he mentioned, that forced him to re-evaluate the way he works.