I don't think you understand what freedom of speech means

So, imagine you and your neighbor are arguing over your grill about football, and the next thing you know, your neighbor calls you a loser, so you call him a cunt, and the next thing you know you are waking up from the patio and he's yelling about using that kind of language in public or something. He's clearly wrong, right? You have a freedom to say what ever you want, don't you?

Next, imagine you're sitting on Twitter, talking about locking up all the illegal immigrants in tent city prisons and forcing them to wear pink. The next day you log in, but your account has been suspended for 24 hours. You have a freedom to say whatever you want, don't you?

Point one, freedom of speech doesn't relate to every day interactions you have. The rights you site aren't so that you can go around being a douche and everyone else can do nothing but listen to you and be owned like you think. It's not about the free market place of ideas, where the loudest voice with the worst idea wins. Free speech means I can say that Donald Trump is a heartless, brain-dead, anti-capitalist, Cheeto-Supremacist who should be stripped of rank and wealth and the government can't come arrest me for saying that.

You missed the difference there, didn't you?

The difference is that a citizen cannot be oppressed by the government for expressing their opinions, ideas, or desires. Any law passed in contradiction to this idea is unconstitutional, but people tend to allow those things to slide because they like anything that makes them feel a little more secure.

A citizen is allowed to stand on a platform and yell their head off about how the president's son's girlfriend's uncle's barber is in the Illuminati, but they are not promised to be given a platform, nor are they promised a crowd that will listen to them. This is where the Twitter example comes in, if you couldn't tell. You are promised a free press, but you aren't promised a voice in the press. You are promised access to ideas if you seek them out, but you aren't promised a searchable, cross-reference-able, link-able, sharable, real-time, archived, and comment-able system to deliver your ideas to people. What are you? Socialist?

If you want to treat Twitter like a public commons of communication, you need to

1. Cover the costs of maintaining the commons. Developers and dev-ops and sys-admins and database managers, the software they use, and the bandwidth both incoming and outgoing, are expensive and someone already put in the investment to source those things. They continue to put in the resources. And if we want to make it a public good, that (those) someone(s) needs to be fairly compensated, and the government needs to take over responsibility for making sure those roles and tools are filled and managed. That means more taxes. Socialism & Taxes are step 1.
2. The workers of Twitter need to be indemnified for the public's usage, or miss-usage of the public commons. Park rangers are not fined or arrested if you shove someone off a cliff at Yellowstone, nor are they jailed if you knock over one of the Stonehenge monoliths. So too would Twitter workers need protection from fines, prosecution, and persecution for you posting death threats to the abortion clinic the next state over, or when you pimp your wife off like some kinda cuckold or something.
3. Twitter would have to allow unfettered government access to the servers and databases, as well as logs, and any other records that are created when you decide to pimp off your wife for use against you at your sex trafficking trial. That's right, there's nothing about Twitter being forced to give you their platform that exempts you from being charged for any crimes you commit using it's infrastructure. And just imagine if those redneck Bundy's decide to take over the servers with guns and inbred cousins like they did that one nature center, and the government has to shut down the power to end it peacefully. What are you going to do then when some other citizen ruins your public access?
4. Of course Twitter would have to be locked up with bureaucracy and legal red tape if you want to post anything globally, because a government service can't be seen to allow Iranian nuclear scientists to receive instructions on how to miniaturize a triggering device for a suitcase bomb from some Anarchist Cookbook kiddy in Whales.

And probably some more I didn't think of, and you SURELY didn't think of. The point is, Twitter is not a public commons, no matter how many people use it. We have analogs to this that conservative and libertarian nutters are always ranting against.
Ever used the term "Obama Phone?"
Ever argued against "Net neutrality?"
What about section 8 housing?
What about single payer healthcare?
What about Euro-zone.
Cancelling Brexit?
TPP?
NAFTA?
Outsourcing?
These are all things that you'd have to support for the sake of logical consistency to support arguments that would support Twitter as a commons.

Lastly, contrary to what we like to think, there never has been absolute freedom of speech. Nor was it ever intended that citizens have absolute freedom of speech. Even while the USA was still young and the original founders still ran the government, the Alien and Sedition act allowed the government to lock up citizens for what they said. And can you blame them? The last time a bunch of drunk guys were allowed to talk seditiously, they stole the New England colonies.