John Lilly publicly confirmed he resigned rather than appoint Eich, without elaboration. I did not say the board resignations had to do with Eich's material support for Prop 8. WSJ stated all three resigned because of Eich's appointment, and none contradicted that report.
https://blog.mozilla.org/blog/2014/04/05/faq-on-ceo-resignat...
2 stepped down because they had other stuff to do, the other 1 because of something that is not prop-8 related.