Perhaps the feature could be designed in the way that it is more of a rumour.
Something along the lines of: "You've heard that Person-X has been sighted around Location-Y not long ago."
This would still leave it more or less IC, as rumours can spread about people. (NPCs do talk, afterall - word gets around.)
On the other hand it should still be toggleable, as the rest of the Debug-messages, for sake of privacy, etc.