Everyone brings their phones to protests because they have cameras and it’s how they communicate with others. Riots are also rarely planned in the US so so I doubt even a majority of the participants will remember not to bring a phone with them.
I understand you’re being somewhat tongue in cheek, but the flippancy of your statement downplays the chilling effect this can and will have on protests and other gatherings. It also impacts one of the most powerful tools we have for accountability: the cameras on our phones.
Notice that Louisiana just banned filming police officers within I believe 25ft. These governors/legislators aren’t stupid. This is all a very deliberate, coordinated effort.