I'm glad you pointed out that you don't live in California. If you did, and had seen the actual campaign, you would know that it was one of the shrillest, most dishonest, most deceitful political campaigns in living memory (which is saying a lot). Indeed, it was the absolute epitome of bad faith, and that would be true regardless of the subject.
When Judge Vaughn heard the subsequent legal case against Prop. 8 he invited the supporters to submit any of the "facts" about the "dangers" of gay unions that they'd cited in their media campaign to his court for consideration. That catch was that they'd have to do so under oath, meaning that any known falsehoods presented as truth could lead to charges of perjury.
The supporters ended up saying nothing. So while it turned out that these supposedly religious people had no real concern about bearing false witness in the eyes of God (who is, perhaps, more forgiving) they were a lot more circumspect about doing so before the State of California.
In terms of lingering ill-will, it's not just the cause people are upset about. It's the extraordinary divisiveness and dishonesty with which it was advanced. And the worst part is that now, after taking such an unambiguous stand against the values of moderation, diversity, and tolerance, Brendan is appealing to those exact values when defending himself against the backlash.
Most reasonable people know that tolerance cannot extend to intolerance, and that preserving a society that is generally inclusive and respectful means getting pretty intolerant with those who attack its ground rules. That's what happened here. And the guy who did the attacking seems entirely remorseless.