Can't imagine there's -any- doubt that while offering the miles on craigslist seller was contacted at some point by a "buyer" and, then.. the result. As (almost) always, more to the OP's story than presented.
As far as the nonsense about if AAdvantage really "gets to do this" (i.e. do they have full authority over the miles they issue-- no matter how (yes, they do),) that's already been firmly established and explained in the main thread.