We know criminals tend to attack anyone they want with BGNPCs alone, but iNPC is listed as an incompatibility. However I think there's some form of unintended support as while iNPC is enabled, criminal activity increases dramatically, as criminals will attack citizens and cops a lot more often. They don't instantly start shooting, they do wait a bit, but it takes a lot less time for them to become hostile and start shooting anything that moves.

Even full gang wars take place on larger scales with iNPC enabled compared to just 1 or 2 shooting a random citizen at one time out of about 75 npcs in the world with iNPC disabled.

Maybe list iNPC as partial (yet unintended) support since it doesn't exactly break Background NPCs, but just makes them more aggressive than normal.