Shortly after it last ran, the developers implemented image moving, but they didn't do a complete job of it: pages that show an image via a redirect don't show up in the "File Links" section of the image description page (or the corresponding API query), so FairuseBot would see them as orphaned.  At the same time, the name on the page isn't the same as the name of the image, so none of my bots is able to remove such an image.  Fixing this and properly testing the fix is going to take a significant amount of work: much of the bot code is based around the assumption that an image only has one name.