nope, only thing this would've shown is that pictures aren't really deleted. Think about it. Facebook would do a rollback and all the pictures would be back. However with a little bad luck on their part they'd mess up which would lead to them restoring rightfully deleted pictures (many of them embarrassing). Would this have happened for sure? Probably not, but I strongly believe that this could have ended hilariously and frankly I am a little disappointed that the researcher was a white hat ;)