That is correct.
In fact, I would point to some of the language here, where, while serious interference with or disruption of an essential service or a system is part of the definition of terrorist activity, it does not include, to go to your point about a peaceful sit-in, lawful or unlawful protest, dissent, or stoppage of work unless there is intention to cause death or serious bodily harm, endanger someone's life, or cause risk to the safety of the public. In other words, your description certainly doesn't meet that standard. Non-violent unlawful protest is not included in this broader definition of terrorist activity.