No one has been banned from Twitter for being black, or jewish.

You see now how absurd that argument is?

If you go into a restaurant and start screaming at people that the election was rigged, or waving a nazi flag, or telling everyone they should storm the kitchen to demand gluten free pasta, they will kick you the fuck out.

And what makes it so? The law, I presume?

If so, then "censoring a user" is equally a crime, because this Polish law says so.

There was no state law against racial discrimination and the bar only used local products so didn’t engage in interstate commerce.

You see, unless we specifically make laws to protect a class of people, private companies will discriminate on that basis.

I guess the question here is do we want to make “people who lie and spread disinformation about important matters” into a protected class. As if is now, we barely discriminate against them. You have to lie for 4 solid months, culminating in a violent riot against the central government before any private entity will ban you.

Nobody is saying anybody should be banned/blocked for who they are - just for what they say.

e.g. Similar to the "gay cake" case (https://www.bbc.co.uk/news/uk-northern-ireland-45789759). Issue isn't that the customer was gay, the issue was the bakers didn't want to make this particular cake for anybody.

Having been born a black or a jew (at least for the genetics) is not.

Edit: more generally, this is something you are vs something you did. The latter is widely considered as acceptable criterion for revoking your privileges or rights.

Discriminating people for what they are (deadly skin emissions aside; I challenge you to come up with a real-world example) doesn't feel fair, neither to those who are being discriminated against nor the population in general. Unfair constructs in the society are likely to cause overall harm in the long term (if nothing else, the society is unlikely to extract the full potential of those who feel unjustly treated by it). So you'd have to have some benefits that are greater (or greater harm avoided) than the likely harm to justify causing that harm.

So voluntaryness is not irrelevant, with a footnote that there might exist a case where it needs to be weighted against other factors.

The argument is not absurd, it only has its limitations and is not absolute. You have shown one of the limitations: Discrimination based on identity is one of them.