I'm for gay marriage and downvoted you. How can you conflate the two aspects? Is it not possible for a person to hold backwards views about certain things and still be a good CEO?
But would he be a credible steward of gay employees if he doesn't even think they should engage in marriage, and by extension forge families? Credibility is the job of the CEO, including moral credibility.
Having a vision which encompasses society and life is part of the responsibility of a company which has been granted license to operate in society. What is Brandan Eich's vision of gay family life? One that should be banned by law, a cause which is serious enough to warrant his financial contribution? His actions as a man of experienced wisdom says Yes.
Any more than you can be a credible steward of Republican employees as a Democrat? It is possible to set aside your personal views of people on the job…
It's hardly ideal. But, to counter - you don't have to trust Brendan Eich that there's no anti-gay, anti-Uyghur, etc code in Firefox.
You do have to trust google, because of the telemetry. Trusting any powerful party based on public, virtuous statements is... "optimistic" is one word. "Reckless" is another.