Amazon can freely choose to do business with whomever they choose to. They have no legal carrier responsibility to host hate speech with violent calls to action if they choose not to do so.
We're nearly at the point where "Feel free to discontinue business with Amazon" makes about as much practical sense as "Feel free to grow your own food." Makes a great quip in social media but is completely unrealistic.
The reason we have government is to solve these kinds of disputes and force businesses to behave. Of course, sadly, nowadays government doesn't act fairly, and will always come down on the side of their political 'tribesmen' rather than faithfully and impartially executing the law.
