He donated money to a political cause directly against some of his employees, got called out on it and refused to compromise. I'm sure those are admirable characteristics in some situations, as the CEO of an organisation like Mozilla they're suicidal. He doesn't seem to get that even to this day, based on some tweets linked to in this chat and in the article.
"Don't be an asshole" is a pretty good philosophy if you're going to be a ceo of an org like mozilla, and donating to an organisation which seeks to deprive a subset of your employees of their rights then refusing to compromise on it sounds pretty assholic to me. I know in the US it's all unlimited free speech, "but I have conservative views" etc etc, but that has real consequences in the same way that going up to a homosexual person in the street and telling them that you don't think they should be allowed to get married would have consequences - maybe they punch you, maybe they shrink off and feel terrible.