The facts:
Judge Walker held Prop. 8 unconstitutional. There was good reason during the case to believe he is gay but he never said he was. No motion was made to recuse him. No request was made for more information (it could have been done in chambers with a sealed transcript). He has now retired. He has since announced that he is a gay man and that he has had the same partner 10 years.
My view: The fact that Walker is gay has no bearing on his ability to sit. I trust no one disagrees with this. Not even the defendants do.
The fact that he is in a long term same sex relationship does not, by itself, have a bearing.
But if he and his partner want to marry in California and only Prop. 8 stood in their way he violated the recusal rule. The disqualification might or might not have been waivable depending on which section it fell under - a or b of section 455. Both are possible.
If they wished to marry but didn't care if it was in California, Iowa or Massachusetts, then whether he is disqualified depends. On what? On whether he and his partner, once married elsewhere, would enjoy a significant benefit if same sex marriage was legal in California. That benefit would likely be financial. That basis for disqualification might or might not have been waivable.
Only Walker knows if he has any interest in marrying -- anywhere. Let's say he does not. He is not recused. But shouldn't he have revealed his sexuality and his relationship anyway so the parties could decide whether to seek recusal?
Yes but. It's always better to reveal a possibly legitimate basis to seek recusal that is not easily discoverable (as through disclosure statements). But we're dealing with what we must acknowledge is a private fact -- sexual orientation. I think the strong presumption in favor of disclosure is weakened when the fact is so personal, not financial. If we also assume that Walker knows he has no interest in marrying, I would not expect him to reveal his sexuality and relationship where the absence of any desire to marry means recusal is not required.
But he might change his mind in a year or two and want to marry in California and his ruling now makes that possible. Not good enough. The conflict cannot be contingent, remote or speculative in the language of the caselaw.
But (this post is full of "buts"), Walker has now revealed his sexuality and his long term relationship. So he doesn't have a strong interest in privacy after all. Since that was the only justification for failing to reveal before, he should have revealed and let the parties make their record, he could put on it what he would, and there would a basis for appellate review. So he was wrong not to reveal.
But what now? A failure to reveal facts that could serve as the basis for recusal is not a basis by itself to vacate the prior decision if the judge would not have been disqualified in the first place.
Any reviewing court has to ask whether the facts warranted recusal, absent waiver, if allowed, and so we're back to the threshold questions: Does Walker want to marry in California? Does he want to marry anywhere and if so will that give him a substantial (probably financial) benefit in California if Prop. 8 is struck?