My usual rebuttal on this topic is that Amazon hasn't registered this term as a trademark so they clearly aren't going to use it. That argument doesn't work anymore because Amazon has taken to registering trademarks just before announcing the product. For example, the Kindle Fire trademark was only filed the day of the press event.
But I still would not read too much into this. Amazon has long had the habit of buying up domain names just to make sure no one else has them. This is actually the 4th or 5th name that Amazon has registered this year. I had posted about a number of the new registrations back in August, but so far as I can tell Amazon never even activated the websites. Surely if they were going to use that name then they would at least redirect it to their home page, right?
On the other hand, Kindle Tutor is a nice name. I could easily see a support service which used that name. It's catchy. Unfortunately, Amazon would probably be rather obnoxious if anyone tried to use it.
And BTW, Amazon may have purchased kindletutor.com but they did not buy the similar sites at kindletutor.net, kindletutor.org, or others. But I did. It's a nice name.