Prop 8 was a constitutional amendment that removed civil rights from a historically oppressed group. That it has been since overturned is largely to the credit of the activists who opposed it before, during, and after it passed.

I can understand this position as well. However, it seems dangerous for us to have a society where we have to be constantly be "saying the right things" or punitive actions are to be taken against us. This does not sound like a free society. Granted, as CEO of Mozilla, he is not in the same position as a typical private citizen, but the principles should still apply. "In radical opposition to some of the most important cultural aims" could just as well be rewritten as "Having political views we don't like."

There is pressure to not have beliefs and practice that are harmful to others. You are free to believe and say whatever you like, but if what you believe and say is "black and white people should not intermarry" or "muslims should be rounded up into internment camps" you are going to face heavy consequences. If you feel you must walk on eggshells because of your views on gay marriage, you may be out of sync with social norms, just as segregationists were in the 60s and proponents of criminalization of homosexuality are today.

"Political views we don't like" - political "views" in the form of many dollars that were intended to and successfully deprived a group of a civil right, and "we" in the form of a vocal, nonviolent nonmajority speaking out online. If you think that doesn't sound like a free society, I think you may not very familiar with what actual non-free societies look like.