Note that it doesn't call for a clear intention of anything.
Take this guy- he doesn't meet the Patriot Act definition of a domestic terrorist.
If you interfere with the operator of an airplane with callous disregard of endangering the passengers that's a crime under the Patriot Act- but it's not domestic terrorism.
But it's domestic terrorism if you have sent a note to the airline saying that you'll endanger the operation of the plane if the government doesn't close down the IRS- or done something else to show intent to firghten the people into doing what you want.
Note that it doesn't call for a clear intention of anything.
I reckon it means "terrorism" is in the eye of the beholder.