I've just looked at both perspectives.
I don't have a better answer from a leadership perspective. I know what I would have done in your place, just as I thought you should have done - stopped responding to Al cold turkey and let his complaints either fizzle out or look laughably passive aggressive. But that's under the assumption it wouldn't have gotten under my skin. Under the assumption that something, at some point, would indeed get under my skin, there would still need to be a viable plan for how to manage it. And then it becomes a question of either dealing with it quickly and harshly, or delegating the task, probably to a small group of admins. I would have a strong preference for delegation, but realistically I can't see either parts or renaeden getting involved - neither one likes drama - and the only other option, McJagger - nothing I said could convince him to come and shake things up. That was why he showed his face for about sixty seconds, btw. I asked him to come and sinbin both of you.
I still think that you should face some kind of repercussion, as a member, for being a provocative asshole.
From the other perspective - well, obviously I've been there. I support free speech and I think it's critical to the health of a community to have people who speak the truth to power. I have good memories of Kamina - she and Pea, as well as DD, on that forum of Pea's, were all good to me when WolFish and I were dealing with one of the interminable health crises. I'm sick to fucking death of Al's broken record, maybe because I don't see you as blameless in the way he seems to be convinced that everyone does. I don't need him to batter me into having a balanced perspective. I can think for my own damn self. I also support his ability to do the same. I'm concerned about moderation creep, even as I see the extent to which it's being brought on as a consequence, not a cause, of the actions of the guy most vehement about its danger. But I know better than to make an issue of it without having a plausible solution.