What this amounts to is that the Kindle owner does not have ultimate control over the books on their Kindle. This is retained by Amazon which can delete them.
This may not matter much now, but imagine a society in which physical books are no longer produced and everyone has their library on an e-book reader instead. Then suppose the government in that society decides to ban Orwell's 1984. One press of a button and 1984 is deleted from everyone's library simultaneously.
Even now, one can see how the potential of e-book readers like Kindle might appeal to regimes like China that want to control their population's access to information and monitor what they are reading.