I'm not a member of mefi, and if you folks frown heavily on Adams' sort of impersonation, that's your community rules, and fine.
But it wouldn't be my community rules to have a moderator out him.
I guess I would like to think that his behavior, while perhaps not exemplary, would get a pass from the outing, because I suspect that such behavior goes on all the time, and you aren't policing, consciously or not, the behavior of people with less famous names.
I would prefer a community where "famous people" who might be mentioned are welcome as participants and I can only see that happening under pseudonyms. Because hey, they should be able to internet too. And a small aspect of that is that as on any online forum, there will be time they act like jerks, or so you and I might classify. And such behavior really shouldn't rise to national mockery.
His statements and the dialog from everyone were actually somewhat interesting.
But as far as that thread went, and your behavior while moderating it, the thread went downhill into a Scott Adams bashfest by the second and sixth's comments.
As a moderator, you allowed ad hominem celebrity bashing in as part of your community rules, but you disliked it when said celebrity comes in to defend himself and suddenly he is outed because he violated your rules.
Well, ... I think your rules that essentially do not permit this guy to defend himself unless he writes under his own name are lousy rules because no one else had to write under their name.
You didn't examine who the pseudonyms of the other commenters were. For all we know, it's his ex-wife, or some feminist blogger still angry with him, or someone else with an agenda.
I don't know what common mefi behavior is -- I think in your position I would have either ignored it, or as a moderator, asked everyone to get back on track and knock off the pile-on.