I have a feeling that the guy just filled up his save space. It happened to me once too a long time ago.
Every once in awhile, you have to move cities, save, and then delete the save of the old city in order to give yourself more space, or else you get the save error they reported. The more often you save, the more often you'll have to do this.
It would be great if we had multiple save slots per character instead of having only the most recent save. That way we could keep on top of what saves we're keeping and getting rid of instead of the saves seemingly all piling on top of eachother.