> Hollywood is a private business as well.
No, it's not a private business.
> They were within their rights to make a blacklist
No, making an agreement in restraint of trade is a violation of the Sherman Antitrust Act.
No, it's not a private business.
> They were within their rights to make a blacklist
No, making an agreement in restraint of trade is a violation of the Sherman Antitrust Act.
They didn't do that, just like the tech giants are not doing that now, as they take the same action at the same time against the same target.
Neither publication not open admission are necessary for a combination in restraint of trade to be illegal, and you'd usually want to avoid them since they make it much easier to prove.