Yeppers on the backup data. I just find it amusing that they came out at first... throwing their hands up saying, "Oh... all the documents were destroyed!" (like they didn't KNOW they had backup data) All of a sudden these files just "happen" to be found. Maybe some internal squabbling as to who was supposed to cover who and what.. then someone felt threatened? I guess we'll see, as the saga unfolds.
Well, I'm assuming contact via law enforcement agencies must have had something to do with that. If they're subpoena'd, and can't answer, then they'd better have a good explanation. Having worked ones from the FBI, they pretty much say "Give us what you have in regards to /insert subject/ by this day /insert date/ or provide an explanation as to why you can not".
I think you're reading too much into if by thinking it was some sort of "security" meausere someone had to cover their own backside. Certainly possible, but knowing how corporations work with data, I'd lean towards standard data recovery was the motivation.