IIRC, it detected him when Radditz specifically stood a few feet away from the guy and told it to analyze him. So it's really a question of at what point the thing would be programmed to have an alert, which we have no real basis for knowing. Someone with a power level that low is functionally incapable of doing Radditz physical harm without an ability like Kitty's, so I suspect he wouldn't have it set up that way anymore than you'd want your phone to tell you when a fruit fly gets to close to your head. He might have it set up that way or he might not, anyway.
Nevertheless, it's all rather moot, as it only comes up if the match starts like, with Radditz sleeping and wearing earmuffs.