Forget piracy, the blogger also had time to read the book and then try to sell it back - for full price. That is still, in the words of the seller "...taking advantage of the system… at my expense."

There is an issue (with Amazon) if there is no "Other" option for the reason of returning the book, but telling the seller "I no longer want/need this" book after (reasonably assumed to be) using the book for three weeks seems disingenuous at best. This implies that you did want the book at one time, you've gotten all the use you can out of it, and now you want a full refund.

Imagine if you go to the car dealership at the end of the life of your car and did the same thing...