Laws are supposed to be crafted to be as applied by anyone, anywhere and at any time. This is why lawyers and politicians are supposed to have foresight and be prudent.
You look at prior events and see them as justified due to the people involved and situations.
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.
When my friends on the left held power and used it to quash the speech of my friends on the right, I spoke up.
When my friends on the right are doing the same, I also speak up.
The sad irony is that those not in power protest only when it is not their side.