On the other hand, there's no absolute right to be a public-facing CEO, and it's not unreasonable for the public to name-and-shame companies for their stances on public issues and the people they choose as corporate leaders.
In some cases, this means right-wing activists boycotting and gay-marriage advocates praising Target for same-sex wedding registry ads; in others, it's blue-staters deciding not to eat at Chik-Fil-A for its right-wing political donations, and red-staters buying that 24-piece combo for the exact same reason. Personally, I do think that Eich did all the right things as far as policy and PR goes, and I'm actually a bit sorry that he's stepping down.
I think that the real sin here was not his political donations, it was the fact that he and MoCo didn't make at least cursory efforts to wargame out the possible PR issues that they ran into, which meant they were unprepared to deal with the firestorms.
It's obvious that a significant number of board members weren't happy with Eich's promotion on strategic grounds, and the Prop 8 issue was just the icing on the big poisonous cake of bad publicity. Generally speaking, if you're the CEO, the company should be in the news, not you, and Eich was getting hammered left and right.