People change. I believe that he could be a good person in a role for Mozilla, despite being against gay marriage. The fact that he steps back from this important role both shows that either Mozilla or Brendan himself are sensitive to the topic. I would like to believe that Brendan has changed (some people tend to do that over the years) and resings as a sign of admitting that he was wrong about the gay marriage thing. This makes the whole situation kind of paradox - him stepping back indicates a kind of sensitivity that I would like in a leader for an organisation like this.