I'm specifically talking about Instigator-spawned threat sitting there or even retreating when faced by enormously inferior forces: I'm aware that specific case is a bug, but it gave me the idea of a failsafe system detecting poorly located/idle threat and putting it to use (even just moving it to important worlds).
Wouldn't help. It was already sitting on 100x my power and not using it. Lowering the threshold would mean bugger all to numbers like that.
Yeah, this is a bug that was fixed last update just now. Instigators are not meant to act as threat, so when it was mentioned, I was thinking about Sentinel/Hunter units, like from CPAs, not Instigators. Bit of a miscommunication there. The threshold for attacking would apply to the mentioned Sentinel/Hunter units, not Instigators.
Instigator units are meant to, as Badger said, attack piecemeal towards your Homeworld. They don't care if they can't win, they just try anyway. When they work, that is.
Apologies for confusion!