Ironically, they are accusing him of being intolerant.
Via Business Insider:
Some employees at Mozilla, the non-profit organization behind the Firefox browser, are calling on new CEO Brendan Eich to resign.
Mozilla workers are upset with Eich because he supported Proposition 8 and donated to the politicians who backed it.
Prop 8 was a Californian ballot-proposition banning same-sex marriage. It was officially rejected in February 2012.
But some employees at Mozilla, such as design researcher Emily Goligoski, feel that Eich’s decision to back Prop 8 goes against Mozilla’s core values as a company. […]
Eich hasn’t hid from the fact that he supported anti-gay marriage legislation. Following his appointment, Eich said the following regarding the LGBT community at Mozilla on his personal blog:
At the same time, I know there are concerns about my commitment to fostering equality and welcome for LGBT individuals at Mozilla. I hope to lay those concerns to rest, first by making a set of commitments to you. More important, I want to lay them to rest by actions and results … I know some will be skeptical about this, and that words alone will not change anything. I can only ask for your support to have the time to “show, not tell”; and in the meantime express my sorrow at having caused pain.