I'm sorry, but you made a mistake of projecting your own beliefs and value system onto Mozilla.
Mozilla is simply a technology organization and their mission is to promote a free and open web. It is not human rights, animal rights, or anything else.
If Brendan Eich believes in a free and open web then he is the right person for the job.
I don't either - I believe in governmental civil-unions for all, and the marriage ceremony (or not) of your own choosing and would allow for stricter contracts to be signed among willing parties.