“If you right click on a game in Steam, you’ll see that you can back up the files yourself. Unless there was some situation I don’t understand, we would presumably disable authentication before any event that would preclude the authentication servers from being available.
We’ve tested disabling authentication and it works.”
but as far as I am aware that was just a post from a random user. It could be that they contacted Gabe himself through his email. It was 2009 and from what I recall he would frequently respond to users back then but there’s not much to back it up currently.