I found this on the FBI website:
“Domestic terrorism” means activities with the following three characteristics:
Involve acts dangerous to human life that violate federal or state law;
Appear intended (i) to intimidate or coerce a civilian population; (ii) to influence the policy of a government by intimidation or coercion; or (iii) to affect the conduct of a government by mass destruction, assassination. or kidnapping; and
Occur primarily within the territorial jurisdiction of the U.S.
Those are pretty broad criteria which seem to be able to apply to just about any crime of violence or intimidation where government law enforcement is involved. Because Frein wrote that he “hoped” people would rise up (in his own mind) does not mean there was a reasonable inclination which would meet the threshold in the statute.
The way this statute is written, a parent shoving a school board member could be classified as a terroristic act. (Not that shoving a school board member is acceptable of course, just that it could fall within the boundaries of this statute).