It's a difficult realization, in some ways, to understand that the messages we receive may often have already been prepared before events take place in our perception of time.
My understanding is that there was an alternative message[1] prepared in case the Apollo 11 mission did not succeed, for example.
It's notable to some extent that the message you've posted here was made public by accident. But those possible-future messages are out there -- and in some ways, knowing their contents would allow us to learn a lot more about where we are geopolitically.
Given the state of data security nowadays, I'd even guess that some "fake" future announcements may be drafted to mislead snoopers. Even without the ability to know for certain what was prepared with authenticity and integrity, the contents could still allow useful inference.
[1] - https://web.archive.org/web/20120724221032/https://watergate...