I think most people view freedom of speech as a right in a broad sense, particularly with respect to the government, but are also okay with a violation of it in certain contexts, like in a private domain. It seems to me that a bar owner kicking out a loud or inflammatory patron is an example of "oppressing that right", but most people understand this and have no problem with it because the alternative -- a world where the bar owner is forced to let the patron say anything they want on the bar owner's property -- is worse.
There's a significant difference between private enterprise and government. For example, no matter how much a business doesn't like you, they can't jail you based on their own set of rules (laws).
I don't disagree with your first paragraph, because of the assumption that there are other bars to go to.
If there are not other bars to go to, and if instead of bars we're talking about vital services such as food, housing, or communication that have been monopolized or oligopolized, then that assumption no longer holds.
I don't think Twitter itself is anywhere near that type of critical. But in general it's ignorant to write off "private enterprise" as if it something that is entirely distinct from "government". And this goes doubly in the US where "private enterprise" ends up shaping much of society.
Sure, I absolutely agree that private enterprise can be a problem and can become intertwined with government. But the topic of this thread is Twitter, and more broadly, Big Tech, and I am not convinced that they are a serious problem in the way that telecom or rail monopolies were. I'm not even sure they are monopolies at all -- there's plenty of competition, even if people choose not to use it. A major difference that I see is that to start a competitor in, say, telecom infrastructure requires a massive amount of capital. To start a competitor with Twitter requires very little capital in comparison, although to succeed requires reaching some network effect.
If an argument about vital services is to be applied, I think it is much better applied to something more foundational to the internet, such as domain name registrars or ISPs.
There's a significant difference between private enterprise and government. For example, no matter how much a business doesn't like you, they can't jail you based on their own set of rules (laws).