Conductive testing could be used for many reasons, but the most common use is to isolate the Bluetooth test setup from the surrounding environment. Interference from radio frequency (RF) sources is the most common reason for isolating the test from the environment. This is especially important when the environment contains RF sources using the industrial, scientific, and medical (ISM) radio bands from 2.4 to 2.485 GHz that are the bands used for Bluetooth.
“Conductive” in this context means that you are not “air sniffing”, that is, capturing Bluetooth transmissions on the Frontline analyzer's antenna. The conductive test setup uses coaxial cable to directly connect the Device Under Test (DUT) to the analyzer's antenna connectors. The coaxial cable provides the isolation from the environment through shielding.