> If the US government can, for example investigate Richard Spencer or some other extremist figure based on a web post, then they can do the same for someone else on the other end of the spectrum.

> But even more terrifying is that they can do the same for someone not in the extremes.

This isn't a valid principle. It suggests that we should oppose laws against murder, because if the government can imprison a murderer, it can imprison someone who saved a life. Even more terrifying is that it can imprison someone who saved a dog's life or didn't save or kill any lives.