The guy has his backups. His problem is not the data. His problem is the human-networking side of things: lots of places linked to his photos (including the flickr blog) and those links now point to dead space. That will reflect badly on him, I'm sure, and not flickr.

If I were Yahoo, I dont care how much it would cost, I would have someone, or someones, recreate his account as it was, even if that meant calling in a data forensics team.