Terrorism generally has specific elements; violence done against civilians for political or religious ends. So the Oklahoma City bombing would be terrorism, but the mass shooting in Las Vegas would not be. Unless calling for the overthrow of the govt includes a call to violence against civilians, it would not fit the traditional definition of terrorism.

Is violent language terrorism? Most definitions seem to include physical violence. But not all.

https://en.m.wikipedia.org/wiki/Definition_of_terrorism