I think Amazon shod follow the law and only sell things which are legal. There are grey areas like "supplements". I imagine they would make a decision based on risk factors.

That said, I think Amazon can decide whether or not to carry a whole category. Sears Catalogs used to sell guns. Congress passed laws and now sales would have to pass muster. But that's altogether different from selling or not selling a service to someone because you think they are "good" or "bad" or you agree or disagree with their point of view.

To me, Patreon is providing financial services, so I think this judgement is not in their purview in the same way Amazon should not judge who is buying or selling on their platform/services. It's none of their business. Is their business legitimate. That's about it.