[serf]

the problem is..

..or ever be accused of overthrowing the government.

..be in proximity of anyone accused of wanting to overthrow the government.

..be victimized by a state employee with a grudge.

..etc etc.

[arrrg]

Is the sole evidence used?

Context, context, context.

[shadowgovt]

Precisely.

By itself, it would just be circumstantial.

In the context of, say, camera footage of you scrambling up a wall of the capitol building, it's extremely important for establishing mens rea, to determine if you were scrabbling up that wall because you got caught up in the heat of the moment or if you had looked up "Is the US Capitol building scalable" a few days before your plane ticket to DC.