Things like this are about ethics, not "American Values" or any cultural norms. It used to be the cultural norm to be a white supremacist but that position as never actually been ethical.
Additionally, in this specific case it's worth noting that the Mozilla Foundation and its subsidiary the Mozilla Corporation are largely political organizations and someone who holds such obviously bigoted views is pretty clearly unqualified to lead an organization who's goals are freedom and openness.
Since you think ethics are absolute and unchanging, can you please tell the rest of us what the one true ethical code is?
I'm pretty sure a much more reasonable interpretation is that ethics are subject to cultural norms, and that we should not decide on one true version of ethics and force that upon everyone.
Obviously there is too much detail and history to lay out the Correct Ethical Choice for every single situation ever, but stuff like "give people equal rights," which is what we are talking about in this case, should be incredibly obvious to any reasonable person these days and judging by the backlash against Eich's appointment to CEO, that seems to be the case.
Alternatively, maybe we can decide on a set of American values and we can investigate and blackball people who hold unamerican views.