They are talking about the comedy club where the owner permanently bans anyone who makes jokes on certain topics. People stop going to it.
Which I think Twitter is going to have to have some standards about what sort of behavior they allow, it's just that there is risk of going too far and making the platform boring and useless. Banning accounts used for harassment is not going too far. Banning accounts because some arbitrary number of people don't like what they say probably is.
I firmly believe that if something becomes as big as twitter (facebook, google, amazon, ...), it becomes infrastructure and should be subject to similar rules as the government. It should no longer be treated like that mom and pop groceries store.
It took people centuries to wrangle civil rights (including free speech and parliamentary representation) from their states - in that process changing them into democracies. Before, all of that was completely unheard of. I wonder if in future, people will fight the same way for free speech on Twitter, universal access to Amazon's shipping infrastructure, the right to be indexed (or forgotten) on Google, and so on.
I'm not talking about free speech. This is a company that didn't censor <x>, deciding to censor <x>. I'm sure the users that discussed/read/were-interested-in <x> will be thrilled. That is all.
I think you mean public company. They went public a few years ago.
ETA: some people made some comments below this that made me want to clarify a few things:
1) Twitter being publicly traded does not automatically make them beholden to every person on Earth, especially in matters of free speech. They're still allowed governing their platform in whatever way they see fit.
2) a better analogy might be a comedy club on open mic nigh.t. If you get up on stage and start making racist, sexist, homophobic, etc. Jokes the club owner has every right to throw you out. Yes, it's a public forum, but limiting your use of what is ultimately a private (i.e. not government owned) establishment does not constitute a violation of your rights unless it can be proven that you were denied access due to your membership in a protected class, or based on your gender, etc. Free speech doesn't protect you from (peaceful and appropriate) backlash.