Ah ok I was not aware of that. I have not flown a plane that had it (I did fly some with G1000 and autopilot but it didn't have this, I think it's only an option on the G3000). But I just saw about the activation button.
It says somewhere that the system also detects if the aircraft is unstable and the pilot has not attempted to stabilise it, or if there's no input for a long time.