This always had a vibe of a conspiracy theory to me. If this were to ever happen and it came out, AWS would be screwed for all eternity. You just need one disgruntled employee to keep a screenshot of their auditing logs to make all hell break loose. I think most companies who actually consider this to be part of their threat model are full of themselves to actually think that Amazon would do this to their brand and the trust associated with it for the benefit of looking into systems that most likely don't contain information that's as interesting as company execs and engineers think.
I once knew someone who forbid his employees to use Google because he said that Google would copy his ideas and that his employees would leak them if they even searched for related key words.