To expand on my idea, the game knows you're in danger as soon as you're in danger.
Simply save this state as soon as it happens, as a sort of tag on your save, with your current mode logged.
The tag is cleared if you legitimately leave danger (die, high/low wake, menu log, etc).
If you force quit, disconnect, CTD ect, the tag isn't removed (because it can't be).
When you next load the game, it reads there's a tag, and locks the mode for 1 hour.
But what is this "tag"? A few bytes of data? Where is it saved? At the FD server (your client may not get the chance to send it)? Or on my disc (so I can just edit or delete it)?
What removes it, the client or the FD server? What if they disagree? What if another player's client thinks I should have a tag when mine doesn't?
I fear you still have a client-server model in mind, not P2P.