As it turned out, he wasn’t. But when they stopped servicing him, they had every reason to believe that he was.
Do you continue to service a customer whose behavior is otherwise unacceptable until you’re absolutely sure he’s a bigot? Or do you abide by your legal obligation to protect your workers from such behavior?
I don’t know if Amazon did the worst thing here, but I don’t know that the best thing is far off from what they did.