I mean, can you think of a better way to make money than to short the stock in a company you know Trump is going to attack? Perhaps you are one of the people egging Trump on about the company. I would think that stockholders and the company itself could sue Trump for using his official position to make materially (and provably) false statements about Amazon causing real economic harm to the company and stockholders.
Mark my words, this is yet another Trump crime that will come to light.