meh, this is a vague term so I have no opinion on whether observing who's at a protest based on the signals their phone sends out counts as a "search". Depends on the supreme court justices' random ideas in practice.
> aren't civil disobedience
> can protest all day long
If protesters aren't breaking any law, we have seen no evidence they have any reason to worry about anything being discussed here. I'm just saying that it's silly to insist on the ability to do so secretly. Masked mobs of anonymous "protestors" is a really bad thing to normalize roaming around and doing whatever they want. Even if most are just nice concerned citizens, you're creating a perfect environment for people who just want to destroy to do so with impunity.
Completely legal protests are met with unreasonable searches, seizures, and even violence all the time in the US. We saw it all the time with BLM. Yes, they need to worry about that.
The fourth amendment: unreasonable searches and seizures. This is an unreasonable search.
Also, protests aren't civil disobedience. Civil disobedience is civil disobedience. Protests are explicitly protected by the first amendment and you can protest all day long.