What on earth do you mean “the silent killer is not a threat to the republic?” The hell you say.
The lone individual is not a threat. The killer in a collective with a great number of like-minded others is a threat. Then there are conversations, notes and a trail of words to identify them. That’s when they need to be identified as a terrorist organization and treated accordingly to remove them from a republic to safeguard the citizens of the republic. That is the primary duty of elected representatives.