"Shill" derives from "shilling", a small unit of currency formerly used in British Commonwealth countries, and referenced in older Bible translations.
In Internet slang, "shill" and "shilling" evolved into a pejorative noun and verb for commercially-motivated inorganic activity.
Whenever someone uses "shill" to condemn non-commercial activity, I assume they are the sort of illiterate who spells "crazy" with an "E".
Solomon's KJV Proverbs already contains a suitably broad pejorative for all flavors of evil, madness, ignorance and idiocy: "fool".
In fact, I daresay this is a more relevant list of pathological behavior than the COINTELPRO copypasta:
https://www.openbible.info/topics/fool