Well, you're forgetting that most people, well at least I am, are more careful when writing formal blog posts vs simple HN comments. So, the minor differences can be attributed to that.

For example, the comment has "/" in google/facebook, while the blog has "Google-Facebook".

What made me curious was not just the topic, and the identity management, google-facebook, but the fact that he is in the field of security/identity management.

But as I said, I dont know if he is on HN or not :)