I think this has been addressed even further into the past... kestas said something like, if it's automatically done and someone is absent for most of a retreat phase (but comes in near the end), they get to know that they have a forced disband, and that's that. However, if the disbands were auto-finalized and everyone else does their retreats earlier, then when the auto-disband guy comes in he'll see a new phase and not know what happen, and think that the game has moved on without him, or has a bug, or was hacked.
That's not to say nothing can be done, though. I propose just making it so that the orders are auto-finalized when the page is first viewed (or some short time after), and maybe have a Javascript alert indicating that the orders are all auto-disbands and will be auto-finalized, and then the reader can see the map where the auto-disband had to happen and why.
That way, everyone is guaranteed to know about auto-disbands, but it's also impossible to hold the game up unless you just never come to the game.
Another option might be to send a message to a user's PM box indicating when a retreat phase with auto-disbands occurs, saying which units were auto-disband, and then automatically finalizing; then the user sees the message when they next log in and the game can move on.