What info is in their database besides these torrents that would be valuable? They don't touch the actual files being shared. I doubt they log anything interesting; if they do, no one's ever going to see it. It would be a huge mistake for them to hand over visitor stats.
Well, you'd have to hit the trackers to pull all the current seed/leech ratio data yourself, if you want to find the living torrents amongst the muck. Things such as number of .torrent downloads, the "PirateBay-verified release" flag, and the comments (yes, there are comments) would also be useful in filtering through them. However, all this stuff would probably be invalidated by the time someone actually wanted to use the backup...