85% willing to bet that 'Logon required' is a symptom of the ubiquitous voteframe problem, which manifests itself in many subtle ways, almost all of which tend to look like the linked-to content is unavailable one way or the other.
eBay auctions will report having expired, even though they haven't, if you go there without the AQ voting frame, for one kooky example.
People swarming content that is missing is actually vanishingly rare, an unexpected blessing balanced out by Merciful Christ through the curse of the AQ voteframe problem.
I guess one day the Alpha Queue will have to stop using frames, and will instead spawn new windows or something equally garish.
Will we miss the Keystone Kops-type comment capers?