I don't see the logic in it. It is hard to make out what kind of lock is used, but for such a dedicated thief wouldn't it be much easier (and faster) to cut the lock and steal the whole bike intact?

For this reason, to me it doesn't look like a single-event theft. It looks more like an abandoned bike that was left in the street for a long time, losing part after part until it eventually got to the stage we see in the picture.