Many of the things the author accuses Amazon of doing are troubling, but the logic the author used in the Chris Brown music buying example to tie it all together shows of a lack of distinction between types of cooperation with evil.
When an act has both a potentially good and bad effect Philosophers like to distinguish the morality of this act of "cooperating with evil" by analyzing the degrees to which your cooperation is:
- formal or material (do you want the bad thing to happen and that's why you're buying from Amazon?)
- immediate or mediate (are you supplying a critical component such that without your specific instance of cooperation the evil could not occur?)
- proximate or remote (Do you work for Amazon?)
Each of these dimensions should be taken into consideration because without such analysis one can easily become scrupulous about every act that one does that may have unintended side effects. This is how you get people who say things like "there is no such thing as ethical consumption in capitalism" and other extreme statements that would otherwise force you to be a monk in a desert lest your acts accidentally create harm.
To learn more about this principle of double effect:
https://thinkingthoughtout.com/2021/01/24/cooperation-with-e...
https://plato.stanford.edu/entries/double-effect/