That may be a good reason to tell passengers to avoid using a laptop, for example. But a kindle? What's the difference between reading a kindle and reading a paper book in terms of "emergency preparedness"? Absolutely nothing.

Also, you're just inventing reasons out of thin air. This is not the reason why the FAA has such restrictions. The reason is that it is very difficult to test a plane as being immune to interference from every single possible handheld consumer electronic device, and it would be too complicated to enforce a selective ban.