The thing is that that concept of business having different responsibilities that scale with size isn't a thing. It doesn't matter if they are a print shop or own half the god damn world they operate on the same principles. That is what make these giant conglomerates scary and why anti trust options and breaking businesses into more smaller options is a good idea. But applying your ideas of government to a business is stupid. If you want a town square get the town to build a square where those rights are protected - don't go down to the Mall owned by a management group and then crow freedom of speech when they throw you out for yelling obnoxious shit in the food court.

Freedom of Speech is a concept - but there are two distinct ones. The actual legal protection and this fictional cootie shot bullshit of "I should be able to say whatever I want and no private citzen or group of private citizens should be able to challenge me in any way". Honestly the second part is just entitlement half the time because last I checked those who usually advocate for the latter are usually the most willing to remove the former from entire groups of people. Personal consequences and social accountability should be and are part of that freedom. There are countries all over the world that have the freedom of speech enshrined in law but every single one places limitations of some sort of how it is protected and exercised . The US for instance has obscenity law, protected classes for whom services cannot be denied and people have the right to sue for defamation or libel. What counts as a legitimate protest (or exercise of free speech) and what gets the unruly unlawful mob treatment is also governed by a web of concepts and law. Free Speech is not an access card that removes all barriers, it's a protection from your government and if you want your government to properly protect you from it you need to increase the space, services and property the government runs on where those rules are protected. You privatize a library you lose a lot of protections immediately because a federal or state institution has to play ball and businesses are closer to autocratic rule.

Freedom of Speech is nebulous and nuanced but in all cases, every single country that protects expression, the responsibility, rights and restrictions given to businesses work on private citizen rules and the right for a private entity to refuse or withdraw participation is just as enshrined.