Youtube has paid staff whose sole duty is to remove videos that violate their TOS. Parler does not. That is the distinction AWS used in there reasonings to terminate service.
That's a private rule and with Amazon as big as it is, we need to have a discussion if a TOS is even legal, if you take a blind eye on that, nothing stands in the way that big company's take over everything, if you want such a world...well then welcome to cyberpunk.
I don't see how you could argue that a TOS is not legal when both parties signed and agreed to it.
Because it clashes often with existing law, many TOS's you can simply ignore (at least in europe) and yes even when you signed it. A TOS does not stand above existing law.