The “agitators” method is a time honored way for totalitarians to keep dissent in check.
All outsiders should be viewed with a jaundiced eye. This is exactly why our government fears “terrorist cells”. This type of closed network has evolved to avoid outsiders.
Patriots are considered terrorists by the current government in DC
What they fear more is leaderless resistance, wherein tiny cells, or even individuals, do what they can without coordination.
Informants can and do infiltrate organizations. How do you "infiltrate" a lone individual who decides to do things, and keeps his mouth shut?