I think Laz could do something close to saying dead-or-alive by just listing a 'last logon' timestamp on the author page (and I'm sure he has the required data already). It doesn't matter if they're working insanely hard IRL, sick, disabled, in prison, dead, or otherwise cut off from the 'net, if they don't log on, they won't be posting. This could extend to 'yellow flagging' as inactive on the 'Authors Starting with...' pages any authors who haven't visited the site for a year (or whatever) - just as the last posting date is highlighted if it's recent, the author name could be highlighted if inactive. [BTW, where does it tell us about what the shading on 'Latest' date means - I'm sure I've seen it, but can't find it now]. Just letting readers know that the author is still around, even if they're not posting, would be a great comfort.
I do think that the underlying author login timestamp should be listed for all noms-de-plume; indeed, I'd like to be able to see all pseudonyms associated with authors.