You should never "update" a post in this thread (or the PGP thread that performs a similar task for that matter) rather, just post a new post containing today's date along with the pertinent details that you provided earlier.
But why that?
I think there's some sort of misunderstanding about the purpose of this thread. Each person essentially signs the ownership of their account. The whole point of quoting the posts is that even if someone compromised their account and changed the message, everybody could confirm the suspiciousness.
In the example above, I don't find a reason to
not update the post. Why to fill the thread with two messages while one of them would be completely useless?