Purity tests / "all or nothing" thinking is reductive. Everyone picks their battles. Ethical consumption is not possible in the light of a global economy.
Are you implying that it's unreasonable for him to dislike Amazon for its labour practices if he's an internet user? That doesn't make any sense.
No. I tried to say that if he wants to avoid things to stop supporting Amazon, then he will have a hard time. A similar case would be Nestle, since they own so many products.
Companies that use AWS are not owned by Amazon. WFM is. There is a big difference there.