This summary is not the rule. The rule text controls.
Any magistrate judge in Idaho has the authority to handle infraction cases, no matter where in the state the offense happened. This means you don't have to worry about whether the specific judge assigned to your case has the power to rule on it. As long as the case is being handled within Idaho's court system, the magistrate has legal authority to hear it and decide the outcome.
Each judicial district may have its own local rules about how cases get assigned to specific judges. But this rule makes clear that every magistrate statewide already has the basic authority needed to handle these cases. It just comes down to which judge within the system ends up with your particular case.