> At least theoretically the humans have some judgement that could limit who they go after or how far they push and can't propagate infinitely.
While the scale is certainly limited, the judgement is not. Cops have been known to use convicted sex criminals, and even medically diagnosed psychopaths to either entrap, provocateur or as foreign agents. There is a famous case in Iceland where the FBI used a convicted sex felon and a known psychopath Siggi Hakkari as a foreign agent to spy in the Icelandic Parliament. (https://en.wikipedia.org/wiki/Sigurdur_Thordarson)
With cops we can safely assume a complete lack of morality and judgement.
They use "bad people" because the rest of the system is predisposed ignore them when they say "the cops made me do X and I have the text messages to prove it".
Compromised individuals become assets because they are easiest to coerce. No one volunteers to do this stuff out the goodness of their heart.