It's more akin to "no shirt no service". Parler can continue using Amazon if they moderate their platform, you can put on a shirt to get a cake. You cannot change your sexuality or skin color.
You can't moderate a platform if there's millions of people posting and only a handful of moderators.
Remember, AT&T is also incapable of stopping criminals from conspiring using text/telephone messages...and based on your logic the Feds could just shut down AT&T and blame AT&T for being "complicit". No obviously that's moronic. Wake up and stop giving our rights away. Eventually you're going to loose your own.