The day Mozilla fired Brendan Eich for political reasons, Firefox died. It just took a while for everyone to realise that. That was when they collectively decided that other things are more important to them than the quality and usability of Firefox. The new CEO is just the final nail in their coffin.
Firing someone for being opposed to same-sex marriage is political in the same way firing someone for robbing a bank is.
That being said, I disagree with Eich and it probably made sense for the org to let him go given how his views might impact public perception of Mozilla.