You should not buy thing from Amazon because their practices are anti-humanity in general, but you shouldn't really be surprised that their cloud servers are being used by Israel. They probably also sell cloud computing to Hamas, and Hezbollah, the KKK, and China, and Putin, and Erdogan, and Kim Jong Un, and Nestle, and anyone else who has a dollar to spend.
AWS is in everything. They don't care what you do as long as you pay them to do it. Boycott the sun, next.
Oh, and their competitors are Google (also mentioned as taking lart in Project Nimbus) and Microsoft Azure. How much do you want to bet that Microsoft is also a vendor for the project?
Don't get me wrong. Amazon has no morals, and we should boycott these massive corporations, but then what? It's not like driving past a restaurant because the owners are MAGA Nazis. How exactly do you propose we boycott Amazon? And even if the boycott was somehow successful, and they pull out of Project Nimbus, would you then be OK with ending the boycott?