Twitter makes it super easy to do mass warrantless surveillance, because Twitter gathers millions of people together in the same searchable public space. It's a honeypot.
What's dangerous about the "public square" concept is that Musk doesn't just want a public square — one public space among many, one among equals — he wants the public square, a monopoly on online conversation. "I think I see a path to Twitter exceeding a billion monthly users in 12 to 18 months" https://twitter.com/elonmusk/status/1596751751532937217
We shouldn't have all of our conversations, political or otherwise, in one place. That's a giant mistake. We need decentralization for our own safety and freedom.
You don't have the expectation of privacy in public in the sense that someone can see what you're doing. But there's also the expectation that a democratic (small d) government isn't watching your every move in public, because that's a sign of totalitarianism.