Let's keep in mind what we're actually discussing here. We're talking about police monitoring public Twitter feeds. They're not tapping phones. They're not secretly infiltrating groups with undercover agents. Just reading stuff that's published in public, for all the world to see.
Reading public messages seems like a super reasonable thing for the police to be doing, to keep tabs on groups that have recently engaged in disruption and violence. Whether those groups are right wing or left wing.
The police aggregate vast sums of data and uses it in ways that the public does not understand, intend, or expect. It's not unlike the way people 'sign' away their privacy on the internet without being aware that their data will then be sold and resold and used against them.
It is a common belief that information is a weapon, and it certainly can be used as one. So does it makes sense, at least from one perspective, that our information should not be legal to catalogue? After all, it is illegal in the U.S. for the government to create a registry of firearms owners because such a registry could be used against the people and its very existence would be an infringement on the rights of those people.
But this information is already being cataloged. It's being published on a platform that explicitly catalogs it, for the public. Anyone tweeting on Twitter is doing so with the full knowledge that anything they say might get signal-boosted by someone with a high follower count and become a major public incident. It happens with extreme regularity. The idea that there is some kind of expectation of privacy here seems far-fetched to me.
We as a collective seem to treat the government as a natural person online, but not in person.
If a police officer sits down at the dinner table next to me and listens in on my conversation with friends and family, I'd be quite uncomfortable. I'd feel equally uncomfortable if they sat across the restaurant and pointed a microphone at the table to record everything. However, suddenly we treat them like normal people if they download the entire contents of our digital lives and process every word we've ever written online.
It's one thing for Twitter to be accessible to natural persons publicly. It's another for a government to treat everyone as though they are under investigation at all times, without a warrant.
For clarity, in my opinion, a police officer who just happens to follow me on twitter because he likes video games is a natural person. However, he stops being a natural person once he starts representing the organization he works for.
Twitter is not a dinner table though. Twitter is a public square. I think you could make a reasonable case for Facebook being dinner-table like. But Twitter has privacy settings. You can protect your tweets if you want to. If the police were breaking into protected accounts, I would agree with you. But Twitter seems about as public as it gets.
Imagine every person in a public square has a police officer following closely behind them with a microphone in one hand a video camera in the other. And we're not even touching on the 3-letter-agency relationships with tech companies which almost assuredly gives them access, even to 'private' profiles.
Innocent people should not be surveilled ruthlessly on the off chance that every now and again we catch one evil person. In my mind, it's like the TSA invading everyone's privacy without ever catching a single terrorist. It's a waste of resources, on top of being a disgusting behavior.
The difference is that in a physical public square, you have a built-in expectation of ephemerality. Everyone expects that their behavior in some random physical space is not going to persist forever. Twitter, on the other hand, is explicitly build with the expectation of what you tweet persisting forever.
On the other hand, there are tons of cameras in public spaces too. So, even though people have had a built-in expectation of ephemerality, that's already been violated for quite a while now.
Reading public messages seems like a super reasonable thing for the police to be doing, to keep tabs on groups that have recently engaged in disruption and violence. Whether those groups are right wing or left wing.