Earlier quoted context omitted.
Fake bomb threats, regardless of how you feel about them, are not violence unless they are accompanied by a demand or seek to compel in some way. TBH as long as there are no real bombs and no one is physically harmed or coerced, I fully support this sort of nonviolent disruption of the surveillance apparatus.
Under law or according to your opinion?
A fake bomb threat where there is no real physical danger, and that threat is not being used to coerce or compel someone, simply isn’t a violent act.
You could make the argument that they are being coerced into leaving the building/stopping work, which would be a valid criticism of my viewpoint, but that is a stretch itself, on top of the already stretched definition of the term.