I agree with your opinion. Amazon will not get into something half-baked as it can possibly affect their name in the world of e-commerce and in fact Amazon get into its top position due to careful, precise and detailed planning. When the time will come that it would be ready to accept Bitcoin then it would be happily announcing it to the whole world. We are just hoping that it would really consider the idea and not just dismiss it without serious consideration. The thing here is that they are looking at it from the view of revenue generation otherwise it would be a big waste of time and money on its part.
Registering domains for the sake of protecting one's name is a good strategy actually and this has been adopted by many big names in different industries and yes even by celebrities I heard. Whether Amazon would be commercially using those domains that we would soon see...they can just parked them if they want anyway. The world of Bitcoin is now closely watching moves from Amazon and many are looking for clues for the possible future inclusion of Bitcoin or cryptocurrency into its very wide and profitable e-commerce platform.