Recall, Mozilla is not a technology company. It is a civil right organization that works in the technology space. It believes that freedom of speech, freedom of assembly, and notably freedom from being spied by upon for political gain by powerful people, can only be guaranteed so long as the technologies that make up the internet remains free, open and controlled by the people -- not by corporations and not by governments.
That is its reason for existence. Everybody within Mozilla powerfully resonates with that mission, else they wouldn't be there.
When we discover that the NSA makes secret deals with private companies to insert spying code into commercial software, which is then used to spy on international leaders during world trade negotiations, the Mozilla foundation redouble its effort to construct a spying-proof browser. Call it applied technological civil right activism.
Civil rights, in essence, means defending the powerless against bullying by the powerful. Defending the poor against class war from the rich. Defending the minority against imposition by the majority.
Thus for the Mozilla Foundation and its supporting community, is it unavoidable that its leadership must be judged by the excellence of their judgement in matters of civil right. Eich failed in two ways. First by taking the heteronormative position, he participated in harming a minority (He has since apologized for that harm.) Second, by using his wealth to bend the democratic process, he participated in corrupting the one-person-per-vote principle that is so important in protecting the voice of the people against moneyed interests.
