The exile survey hacker isn't the same as the survey ship in its working. You use it on AI worlds, and get a general direction of where the Blade is based on distance from the first point and distance from the surveyed planet. (and occasionally get the information anyway if you capture a planet.)
When the filter says 4 hops, it means that from [marked planet], the blade is within 4 hops of that one in some direction. A planet that shows zero hops is the planet with it hiding on it.