I had an e-mail exchange with Zac Woodall, the Access program manager, and Clint Covington, who also works on the Access team but I don't know his title or role. Between the two of them, here is what they offered:
(Zac) I'm sorry to hear you're having issues with the comment post functionality MSDN gets from Telligent's Community Server 2.0This brought up two issues. First, I really hate it when a company uses a third party product and then blames the third party for the product's shortcomings. Second, looking at the Access team blog I couldn't figure out how to create an MSDN account because it doesn't have login/logout links. Other MSDN blogs do (in the upper right). I created an account but I haven't tested Clint's theory yet. If it works it's a pretty lame implementation, but that's been par for the course so far.
(Clint) Have you tried to create an MSDN account?... I think it should solve the problem for you.