Private companies still have to follow the law. What you mention would be anti-net neutrality and thus illegal.
But! That brings up a great point, because I certainly am a proponent of net neutrality laws: would/should such laws not also apply to major internet infrastructure providers such as AWS, thus making it illegal for them to block/ban sites at their leisure?
It effectively does, since revocation of Obama-era net neutrality rules is still being litigated in courts and all providers are still following them while they wait for a decision. Now that the Democrats control the Senate, the House's net neutrality bill which passed in 2019 and was blocked in the senate by Republicans will likely become law.
> would/should such laws not also apply to major internet infrastructure providers such as AWS
Net neutrality applies in the other direction. Comcast can absolutely ban you, the consumer, from using its service if you run afoul of their terms of service, as can AWS.
That's because net neutrality does not exist today. Like I mentioned in my first comment, there are no NN laws in the US.
NN has long stood for the principle of dumb pipes, regardless of you being the sender or receiver.
You edited one of your earlier comments to mention the 2019 NN law that passed in the House; I encourage you to go read that law, as it specifically strengthens consumer protections in regards to ISPs and makes it so that Comcast could not refuse to serve you based on whatever arbitrary restrictions they want. If you are downloading torrents illegally, they could ban you. But under NN, they could not ban you because you were, for example, sharing legal content that Comcast employees have political disagreements with.