Yes, the article has changed, unless I'm going crazy. Previously the link pointed to a different blog post (not on Tumblr) which speculated that MtGox had used custom code to generate private keys for their cold wallet, failed to test it thoroughly, and then discovered that a bug had caused the private key to not match the public address. I was speculating under that assumption.

EDIT: On second thought, I may have confused it with this link posted elsewhere in the thread: http://letstalkbitcoin.com/somethings-not-right-at-gox/#.Uw7...